Best AC Coil Cleaner – Keep Your Coils in Good Condition

​The air conditioner is a modern development that most people can’t live without. With temperatures rising all over the world, the summer months can become unbearable due to the heat and humidity.

Fortunately, there’s no shortage of air conditioners that home owners can install to combat the heat and humidity.

Air conditioners are known to be significant investments and if you’re not doing proper maintenance, there’s a good chance that your unit will break down faster than expected. One of the most common problems that plague most AC units is dirty coils. With a dirty coil, the performance of your AC unit will likely be affected and trust that your bills will go through the roof.

The best way to maintain such coils is to clean it with an AC coil cleaner.

For this post, we will talk about the importance of cleaning your AC unit’s coils. Plus, we have made a list of some of the best cleaning agents and tools that you can use for cleaning the coils.

Comparison Table

Why You Need to Clean Your AC Coils

Nu-Calgon 4171-75 Evap Foam No Rinse Evaporator Coil Cleaner, 18 oz.

image via Amazon

The AC’s coils are some of the most important parts of the unit. Basically, there are two types of coils in an air conditioning system: the evaporator and condenser coils.

The evaporator coils absorb the heat and humidity from the air within the space. The condenser coils, on the other hand, expel that heat outside of the house or building.

So why should you bother cleaning your system’s coils?

Well, if the coils are covered in dust, dirt, and debris, they will not be able to effectively transfer heat. This can lead to all sorts of problems from the system overheating to higher energy consumption.

For the coils to transfer heat properly, the surfaces must be clean. When the exterior of the condenser coil is caked with dirt and grime, the heat becomes trapped inside and will not be properly released. Because the condenser coil is part of the outdoor system, it can get covered with dirt, smog, and other contaminants.

If the evaporator coil is covered in dirt and grime, its ability to remove heat and humidity from the room will be compromised. The evaporator coil is located inside the system so it’s frequently exposed to dirt and dust. This is especially true if you are not regularly cleaning the air filters where airborne particles can clog up the evaporator coil.

​What Happens When You Skip AC Coil Cleaning?

ComStar 90-100 Coil King Professional Grade Concentrated Alkaline...

image via Amazon

If you value your investment for your home cooling, you should do regular maintenance and cleaning of your air conditioning unit – that includes the cleaning of the coils.

Otherwise, expect the following consequences:

  • Higher energy consumption – When the AC coils are dirty, your unit will have to work harder and run longer in order to keep your space cool. This means higher energy consumption which also means more expensive bills. Just because you have an “Eco-certified” unit, it doesn’t mean that you should skip on maintenance and cleaning.
  • More breakdowns – A system that works harder and longer will eventually run into a wall. Because the unit is always pushed beyond its limits, the parts will wear out faster and may lead to a breakdown.
  • Shorter lifespan – Failing to clean and maintain your air conditioner in general is a good way to shorten its lifespan.

Regular maintenance and cleaning are the best ways to protect your investment. Most AC units are located outdoors and the outside elements can really wreak havoc to your air conditioner. Regular maintenance ensures that your coils stay in good working condition.

​Which is the Best AC Coil Cleaner?

​For this section, we list some of the best products that you can use to clean the coils of your air conditioner.

Nu-Calgon 4291-08 Nu-Brite, 1- Gallon
  • Manufacturer model # 429108
  • Genuine replacement part
  • Nu-Calgon item



​Condenser coil cleaner

​Net contents

​1 gallon

​Key features

​Non-acid, alkaline-based product, Formulated with the best available foaming detergents, Quickly penetrate and dissolve greasy dirt and grime, Foams and brightens

The first product on our list is the Nu-Calgon 4291-08 Nu-Brite which is an alkaline-based cleaning agent for the condenser coil.

What can we say? This stuff really works. The product creates a foam that will then proceed to melt all the dirt and grime that built up on the condenser coil. The mixing ratio is 4:1 which is sufficient enough to get the job done. Sometimes, I don’t even need to scrub.

This is a rather caustic cleaning age, so please use proper protection when using this cleaner. If you are not so sure on how to use the product, there are plenty of videos online that can help.

Air Conditioner Condenser Fin and Refrigerator Coil Cleaning Whisk...
  • PROFESSIONAL QUALITY - Same tool used by HVAC plumbing and heating contractors
  • SAVE MONEY - Clean your appliances yourself and save expensive maintenance costs
  • INCREASE EFFICIENCY - Regular cleaning of your appliance increases its efficiency and lowers operating costs



Whisk brush

​Net contents

1.06 ounces

​Key features

Used by HVAC plumbing and heating contractors, Multiple uses,
Strong bristles

Aside from the cleaning agent, you also need a brush or applicator to get the job done. The Midwest Hearth Air Conditioner Whisk Brush will definitely help you get the job done.

While you can certainly use some old brushes for cleaning the coils, using the right tool matters. This is the type of brush that is used by HVAC plumbers and heating contractors, so you don’t have to be concerned if you’re going to damage anything.

This brush has synthetic bristles which means that it can clean the coils effectively without being damaged by cleaning agents. The bristles are tough enough for a thorough brushing but it’s not that hard that it can cause damage to the coils.

Keep this one handy for your regular AC maintenance.

ComStar 90-100 Coil King Professional Grade Concentrated Alkaline...
  • Comstar’s coil King is a premium external alkaline condenser coil cleaner and brightener for coils located outdoors
  • It restores heat transferring qualities to 100 percent efficiency by removing lint, grease and dust and dirt build-up
  • Stronger than most, the foaming action pushes out these contaminants from between the aluminum fins



Condenser coil cleaner

​Net contents

1 gallon

​Key features

Premium external alkaline condenser coil cleaner, Restores heat transferring qualities to 100 percent efficiency, Foaming action

The ComStar 90-100 Coil King Condenser Coil Cleaner is another alkaline based cleaner with a serious coil cleaning pedigree.

This cleaning agent also foams but not as much as the previous cleaner. However, the lack of foaming action doesn’t mean that it’s will not remove the dirt and grime from your condenser. Quite the opposite, it does a great job of removing any undesirables from the coil but it doesn’t corrode the materials.

The cleaner is available in multiple different amounts and is typically diluted with 3-10 parts of water. The correct ratio will depend on the amount of buildup on your coils. For the first usage, it’s best that you follow the instructions from the label. It’s also worth noting that this alkaline cleaner is quite affordable as well.

Nu-Calgon 4171-75 Evap Foam No Rinse Evaporator Coil Cleaner, 18 oz.
  • Evap Foam will liquefy dirt, grease, oil, and other residues quickly and easily
  • Since it is fortified with corrosion inhibitors, it is safe for use on metals and other materials
  • The product’s fast-breaking foam is completely self-rinsing



Evaporator coil cleaner

​Net contents

18 ounces

​Key features

No rinse, Foaming action, Heavy duty detergent, Non-corrosive,
Self-rinsing on condensate-producing coils

Now, we have another product from Nu-Calgon and this time, it’s an evaporator coil cleaner. The Nu-Calgon 4171-75 Evap Foam No Rinse Evaporator Coil Cleaner
is another heavy-duty cleaning agent that I really like.

The detergent will start foaming as soon as it comes in contact with dirt and grime. I don’t know about you but I really love when a cleaning agent foams because I feel like it’s really doing a deep-cleaning job. It comes in an aerosol can so it’s really a breeze to apply. Just point and squeeze.

This is a no-rinse formula which means you can just spray and then leave the foam to evaporate, and then you’re done. While it’s a good convenience feature, I still tend to rinse off the detergent for a more complete cleanup. But that’s just me.

This product smells great as well.

Frost King ACF19 Foam Coil Cleaner, 19Oz, 19 Ounce
  • Heavy-duty foam dissolves stains, removes grease & oil, and loosens dirt
  • Cleans coils, fan blades, and reusable air filters
  • Neutralizes odors from standing water in drain pans



Evaporator/condenser coil cleaner

​Net contents

19 ounces

​Key features

Foaming heavy duty detergent cleaner, Low VOC formula, Fin
Scrubbing Cap, Water based formula, Pleasant lemon fragrance

The A/C SAFE AC-921 Air Conditioner Coil Foam Cleaner has landed on this list because it is both an evaporator and condenser cleaner.

This detergent-based cleaner works wonders in removing those resilient stains and grime from your AC coils. Since it’s a spray, you can just easily aim the nozzle and fire away. The product is formulated to be non-corrosive so you can just spray and forget, without the need to rinse. However, I would not recommend doing that.

The cleaning agent also has a pleasant smell which just can’t be said with similar coil cleaning agents in the market. This is also a fairly versatile AC coil cleaner because you can use it for other cleaning jobs like your car radiators, lawn mower engines, refrigerator and freezer coils, dehumidifier coils, and more.

CRC 3196 Foaming Coil Cleaner, 18 oz Aerosol Can, Clear/Yellow
  • Does not require rinsing in most cleaning applications
  • No flash or fire point
  • Low odor formula



Evaporator/condenser coil cleaner

​Net contents

18 ounces

​Key features

Heavy duty foaming detergent, Alkaline detergent blend, Low odor
formula, No-rinse formula, No class I or II ozone depleting chemicals or
chlorinated solvents

The CRC Foaming Coil Cleaner is another spray foaming detergent. This is an easy recommendation since it can be used to clean both the evaporator and condenser coils.

This coil cleaner is quite similar to the other spray detergents on this list. It’s very easy to apply as you just have to spray directly into the coils without the need to mix water and the solution. Again, this is a no-rinse formula which is a nice convenience feature.

What I like best about the CRC cleaner is the fact that there are no harmful that are used to formulate the product. This means that you can have the peace of mind that you’re not damaging the ozone. 

Schaefer Brush 2026, Condenser Fin Whisk Brush
  • Plastic handle whisk brush
  • 100's of various uses
  • Plastic handle, great for cleaning condenser fins and evaporators



Whisk brush

​Net contents

0.16 ounces

​Key features

Plastic handle whisk brush, Multi-purpose, Plastic handle, great for cleaning condenser fins and evaporators, HVAC whisk brush

Lastly, we have another brush for your coil cleaning needs. The Schaefer Brush 2026 Whisk Brush is another excellent applicator for cleaning your coils.

Well, nothing much to say about this brush than the fact that it’s a very necessary tool. This brush can effectively remove all the junk that accumulates on your air conditioning condenser, especially those darn cottonwood.

Again, it’s hard to go wrong with this one as it’s frequently used by HVAC professionals.

Keep Your Coils Clean

​That wraps up our quick guide and list of the best cleaning agents and tools that you can use to clean your AC coils.

When using these cleaning agents and tools, please read the label and follow the application guidelines. You don’t really want to risk damaging your AC unit or worse, injure yourself.

Keep those coils clean!

Featured Image: Image via Amazon

Air Conditioner Filters: Easy Steps To Replace It


One of the key elements that are needed to ensure that AC units functions at their optimum capacity are air conditioner filters. Although they are hidden and don’t carry as much weight as the compressor, air conditioner filters need to be given a lot of attention. That’s exactly why new AC models come with check filter indicators.

But one thing that many people don’t realize when it comes to air conditioner filters is that replacing them is an easy DIY project. As much as your HVAC repairman may love coming to help you keep your air conditioner in tip-top shape, I know they don’t want to unnecessarily charge you for something you can do for yourself.

No products found.

So how do you change air conditioner filters?

man checking the air conditioner filters

That’s an extremely great question. But before I give you a direct answer, let’s briefly take a look at the importance of air conditioner filters.

Air Conditioner Filters – What are they and Why are they So Important?

Ai conditioner filters are devices made from fibrous or porous materials. They aid in removing solid particulates such as dust, pollen, mold, and bacteria from the air that passes through the air conditioner. These AC filters are placed strategically in an air conditioning unit in order to keep pollutants from affecting the quality of the air the air conditioner channels into your home.

So why are air conditioner filters so important?

putting a air conditioner filter

1. Air Conditioner Filters Protect You fro m Harmful Pollutants

By virtue of their purpose, air conditioner filters filter out pollutants from the air outside and prevent them from being channeled into your home. This will protect you from allergens and other pollutants that can affect your respiratory organs.

In essence, clean air conditioner filters mean better indoor air quality for you and your loved ones.

2. Air Conditioner Filters Affect the Performance of Your AC Unit

As the air conditioner filter in your AC unit becomes dirtier or worn out, it starts to negatively impact of your AC unit. For one, because the pores in the filter are clogged, the blower will have to work harder. This extra strain will increase the rate of wear and tear on your air conditioner.

The opposite is also detrimental. An air conditioner that lets in dust and other particulates will lead to the components of the air conditioner getting damaged. The result of both effects is that there will be a decrease in comfort as the air flow and air quality won’t be as good as they should be.

And because of that, air conditioner filters need to be replaced regularly, and that’s also why you need to learn how to do the replacing yourself.

How to Replace Your Air Conditioner Filters – 6 Easy Steps

man replacing air conditioner filters

It is advisable to change air conditioner filters at least every 2 months. And when it is peak season once a month may be the best. Because of this frequency, you will end up burning a big hole in your pocket if you call your HVAC technician every time you need to replace an air conditioner filter.

To save you from blowing your money away, here’s the easy way of replacing your air conditioner filters.

1. Turn the Air Conditioner Off

When it comes to working with electrical appliances, one cardinal rule should never be ignored when repairing or maintaining it – make sure the appliance is completely switched off. This will make sure that you don’t run the risk of getting an electric shock as you work – something that can be fatal.

Another safety measure you need to take before you go ahead and replace your air conditioner filter is to put on a face mask and goggles to prevent dust from getting into your nose and eyes. Remember, the dust and debris trapped in the filter can be dangerous.

2. Locate the Air Conditioner Filter

Air conditioner filters are located in different locations depending on the type of air conditioner and the model you have. The best way to figure this out is of course to check your owner’s manual. But more often than not, air conditioner filters are located behind the main vent that lets out the cool air into your house.

Although most air conditioners may require you to take out a few screws in order to reach the filter, many new models now feature a slide-out filter. Another advancement in air conditioner technology that you nwill appreciate is that many filters are washable. This concept, however, has confused a few people as they assume that washable air conditioner filters don’t need replacement at all. This just isn’t true as they do need replacement, some every year depending on the manufacturer’s recommendation.

3. Remove the Old Air Filter

Once you have located the air filter, gently take it out being careful not to bump it onto anything as that will cause all the dust and debris to fall out on your floor. Make sure to dispose of the old air filter properly. If it is your first time removing the air filter, make sure to be extra careful to note the direction the filter faces and the type of filter your air conditioner uses. This will make it easy for you to put the new one in.

4. If the Filter Simply Needs Cleaning…

If the filter you are using is washable, make sure to note the date you are doing so. Dust it off, clean it with a damp cloth, and let it air dry.

5. Getting a Replacement Filter

If your air conditioner filter needs to be replaced, make sure to note the model number of your air conditioner, or better yet, of the filter. This will make it easy to know the exact type and size filter you need. If possible, you can carry your old filter with you as well. It can make it easier to find an alternative if the exact match is not available.

When it comes to getting a new filter, many people wonder whether they should get a HEPA filter or not. Well, this is debatable but in most cases, the simple truth is that most residential air conditioners can’t handle HEPA filters. This is because HEPA filters are made of a very fine mesh fabric that restricts air-flow. In order to get air to pass through, you will need a high-powered blower to do so. Something most residential ACs don’t have.

You are actually better off getting high-efficiency air conditioner filters. These work as well as HEPA filters do but don’t restrict air-flow as much.

6. Fit the New Air Filter

Now that you’ve succeeded to get a replacement filter, it’s time for your next victory – fitting the new filter. Before you fit the new filter, you will need to note 2 things first.

  • The date.
    It is important that you note the date you are fitting the new filter as it will help you have a rough idea of the next air filter replacement date. Although most modern air conditioners come with an air filter indicator, taking note of the date will still prove to be useful in keeping tabs on the efficiency of the air filter.
  • Air-flow direction. Noting the direction in which air flows will help you know which direction the new air conditioner filter should face. 

Fitting the new filter is basically the reverse process of removing it.

Air Conditioner Filters – Your AC Unit’s Lungs

a person's hand holding a air conditioner controller

Taking care of your air conditioner’s filter is something that you need to take seriously and religiously. After all, air conditioner filters are like your air conditioner’s lungs. Failure to do so may actually have a big impact on your own lungs as well. So please do take care to replace your air conditioner filters regularly. Your health depends on it.

How Much Does It Cost To Replace An AC Compressor?

AC compressor

Out of all the parts of Aircon units, the compressor is easily one of the most important. Unfortunately, like all parts in machines, it's going to wear out. When that happens, replacing the AC compressor is usually cheaper than replacing the entire unit. Here's what you can expect.

Recommended AC Compressor

Replacing The AC Compressor In A Car

Motorcraft YH-1829 A/C Blower Motor Switch
  • Purchase Price is 1 Each
  • Country of Origin: China
  • Part number: YH-1829

Prices for a new AC unit for a vehicle typically range from $ to $$, depending on the size and style, with another $$ to $$$ for labor. You don't have to buy the labor if you're capable of doing it yourself, though it's always better to let a professional handle it if you're not sure you can take care of it.

Several factors influence the price you should expect to pay, starting with whether or not you want to get aftermarket parts. Unlike some other parts of the vehicle, it's okay to get
an aftermarket AC compressor. In most cases, they make little or no noticeable difference in the operation of the AC unit. Since the quality is about the same, the lower price makes them a smarter purchase.

ac compressor of a car

While many stores sell the AC compressor separately, there's one major problem with doing the replacement yourself: the refrigerant. You cannot merely drain the coolant the way you would oil. Improper drainage of this chemical can be dangerous, and you need a particular machine to remove it. Unless you have one of the most unusual houses in the nation, you don't have this machine at home.

Fortunately, there is a solution. Most mechanics have the necessary equipment, and many of them will be willing to drain the refrigerant from your car for a small fee. This is much cheaper than the labor cost of a full repair job, and it's the best way to go if you want to do it yourself and save some money.

Whether you want to do it yourself or you're willing to pay for someone to do it for you, remember to look around and find a mechanic with a good reputation. Don't be afraid to get competing offers. The last time we needed work done on our vehicle, the second garage we checked gave us a bid that was half of the other location's offer. It does pay to shop around.

Replacing The AC Compressor In A Home

UAC CO 29002C A/C Compressor , grey
  • Brand New, OE replacement: UAC branded 10S17F Compressor Assembly
  • Premium ISO/TS 16949 quality; tested to meet or exceed OEM specifications
  • Includes: body, clutch, pulley & coil; compressor may come charged with shipping oil to keep the part lubricated during...

This is trickier to price than replacing the unit in a car but on the whole, the fact that the parts of Aircon in homes are more substantial means that it's more expensive to replace them. Here are the primary factors that will determine the price.

Tonnage/Compressor Size

Tonnage sounds like it refers to the physical size of the unit or how much air is moved, but neither of those is correct. The tonnage of an AC compressor refers to how much heat is removed from the air, and the compressor size is directly correlated to the tonnage size.

This is a case where bigger is not necessarily better. If you're thinking about 'upgrading' to a better air compressor while the old one is broke, stop right there. If your compressor is too small, it will overwork itself and never shut down. That will drastically increase your electricity bill and wear the parts out much faster.

On the other hand, if your unit is too large, it will turn on and off more than it should. That will also wear out the parts, and worse, it can lead to uneven temperatures in your home as everything experiences rapid heating and cooling.

All Systems Mechanical, an installation company, has an excellent guide to tonnage and room sizes for home AC here. Note that these sizes are for central air conditioning units, not individual room units. Those are much smaller, easier to calculate, and easier to replace in their entirety if a significant part fails. (This may be cheaper, especially if they're on sale.)

Your central AC unit should have a waterproof sticker on it that states the tonnage and other relevant information. If you don't know - and most people don't - check for this. If you don't have a label, you may be able to research it online.

Labor Costs

This varies mainly on location. In cheaper areas, you can expect a price of $$ to $$ for labor, based on the size of the unit you’re replacing. In more expensive areas, prices typically range from $$$ to $$$. As always, it's best to get several bids to be sure the first one isn't trying to cheat you.

Avoiding AC Scams

AC Compressor & A/C Clutch For Chevy Silverado Suburban Tahoe...
  • This is a replacement for the Denso 10S20 AC Compressor. The A/C Clutch is pre-attached at the factory. On 1999-2002...
  • Guaranteed Exact Fit for easy installation
  • 100% BRAND NEW, premium ISO/TS 16949 quality. Tested to meet or exceed OEM specifications

Believe it or not, there are scams related to replacing AC compressors. Here are the most common scams and how to handle them.

Scam #1: Suggesting Parts Need Replacement When They Don't

This is usually done by technicians who want to sell you a whole new unit, rather than accepting the lower pay for a repair job. In most cases, an AC fails because of one part going bad. This is easily prevented by getting multiple bids for the repair job - if everyone says various elements need replacement, you know they're telling the truth. If only one does, avoid them.

Scam #2: One Bid Is Way Lower Than The Others

Cheaper is better, right? Well, not always. If a bid is too far below the others you get, it's probably because the company is willing to cut corners and hopes the lower bill distracts you. A smaller invoice now is not worth it if it's going to lead to another repair job when all is said and done - maybe even from the same company that did a shoddy job in the first place.

Scam #3: Not Providing A Written Agreement

Every reputable company will provide a written quote - usually on a standard form describing the job - before they leave. The reason for this is simple. They know that having an offer in your hand can help them land the job, especially if you're comparing prices from several different companies.

Any company that refuses to provide a written agreement about the job is probably doing something wrong.

part of an ac compressor

Scam #4: A Salesman Shows Up

Air conditioner repair jobs do not require a salesperson - all they need is a technician. Every reputable company knows how to get the parts they need and, in general, they're not going to give you any additional things to choose from.

The repairman might ask if you've had any other problems, and they may try to sell you on a full inspection of the rest of your HVAC system. That's okay - you can say yes or no. However, if someone tries to show you a bunch of new systems and talk you into buying something you don't need, send them away.

Scam #5: Selling Too Much Refrigerant

This is one of the sneaky things technicians may try to do. By "selling" more refrigerant than you need, they can discreetly increase the price of the job. In most cases, the coolant they add needs to be weighed before and after the installation, with the numbers recorded in an ongoing ledger.

The best way to deter this is simple: Watch the repair job. If you observe the technician, chances are they're not going to try and cheat on the numbers. You don't need to loom over them or anything - merely keep an eye on things from a reasonable distance.

Scam #6: Insisting The Unit Needs Immediate Replacement

Unless your air conditioner is literally on fire, it doesn't need to be replaced immediately. This is a scare tactic that some companies use to try and pressure you into buying an expensive new unit without thinking about it. Even broken parts like leaking pipes are relatively easy to replace, and it costs far less to do so than a brand-new unit would.

Scam #7: Charging For Extra Work

Technicians cannot charge you extra for additional work that needed to be done on the parts of Aircon in your home. Any extra labor, like replacing other parts to get at the broken one, should be included in the original estimate. Hold firm and only pay what's listed in the written agreement.

Getting multiple estimates helps stop this scam, too. If all that extra work needed to be done, you can ask, then why didn't anyone else notice it when they inspected the unit? There is no reason to believe that a group of professional inspectors all failed to see some work.

Scam #8: Demanding Cash Upfront

No. Reputable companies do not ask for cash payments before they do the work. If a technician asks for this, politely ask them to leave and tell them that you're no longer interested in their services. They may not even be working for a real company.

Checks and cards are a much better choice. Most of them come with added consumer protections and can be reversed if there's a problem with the service you received. It's far harder to get your cash back.

This Is How To Test A Capacitor For All Heating And Cooling Needs

Heating, ventilation, and air conditioning systems are vital to any home or building space. To maintain comfort and interior air quality, regular maintenance of these fundamental systems is required.  Although diligent maintenance will help prevent any errors, a system malfunction may occur unexpectedly. One of the main elements to examine upon any HVAC system glitch is the capacitor. Below, we have gathered three of our most recommended trouble-shooting methods, which will help guide you in how to test a capacitor.

Notes on Capacitors


Capacitors are essential voltage storage units placed inline to an electrical component to ensure a constant supply of energy. This is done through the processes of charging and discharging. If the voltage is too high, the capacitor will reduce it. If the voltage is too low, the capacitor will fill the gap with its held charge. Placing a capacitor within an active circuit will either build and store a charge on one of the conductive plates, or it will act to absorb any extra voltage passing through the capacitor. The role of the capacitor depends on the system it is operating in and its classification as electrolytic or non-electrolytic. Within one system, it is common to have multiple capacitors with different functions. Although there are varying functions among these capacitors, it is possible to test capacitors with the same methods. We will now explain how to test a capacitor using three different methods.


Please consult with an HVAC professional before performing any repairs if you are not a fluent electrician/engineer. Knowing how to test a capacitor is likely out of range for most people. It is important to remember the dangers of working with electricity. System maintenance can be harmful to you and should be performed with extreme caution and skilled know-how.

How to Test a Capacitor​ in 3 Ways

Method 1: Using a Digital Multimeter with Capacitance Setting

One of the easiest and most accurate methods to test a capacitor is to utilize a digital multimeter that carries a capacitance setting. This is a common function that is found on most mid to high-end readers. The test can be performed by carefully following these steps:

Before You Begin

Before beginning, it is important to disconnect the capacitor from the circuit board and discharge it completely. A great and easy way to discharge the capacitor is to attach alligator cables to both the leads of the capacitor and a resistor. If you have more questions about this step, you should consult a professional as to avoid any potential harm. We are providing this article to help inform people with prior knowledge of electric components in HVAC systems and to suggest our preferred methods of how to test a capacitor to more easily determine whether it requires replacement.

First Steps

Note the capacitor rating which should visible on the body. This capacitor rating is printed alongside the voltage rating on the side of the capacitor. Set the digital multimeter to its capacitance function. Attach the multimeter probes at the proper terminals of the capacitor which you are testing. If you are working with a polarized capacitor, it will be necessary to connect the red probe to the positive slot of the capacitor (this is typically the longer lead of the two). Then, position the black probe with the negative terminal of the capacitor. If this capacitor is non-polarized, then it is inconsequential which way you will attach the probes as there is no polarity.

Take The Test

After assessing the polarity and securing connections between the multimeter and the capacitor, you are ready to observe the readings. You may consider it a “good capacitor” if the values on the multimeter are close to the noted values written on the body of the capacitor. If the values differ significantly or if the reading measures as “0”, the capacitor is “dead”, and it will need to be replaced. We recommend this method of how to test a capacitor because it will give you the most accurate results for the specific capacitor you are testing. It is possible to use this method on various capacitors within the ranges of a few nanofarads to hundreds of microfarads.

Method 2: Using a Digital Multimeter without Capacitance Setting

If you are using a low-end or cheaper digital multimeter, it will probably not include a capacitance setting. We can still test a capacitor using this multimeter; though, the steps will be different. It is important to note the difference between this method and method #1. Though this method may not be the most accurate, it will help you in determining a good capacitor from a bad capacitor. The point of sharing this option is to inform you of the many ways of how to test a capacitor. Also, note that there will be no measurement of capacitance with this method.

Before You Begin

As stated previously, it is necessary to discharge the capacitor entirely before proceeding. Carefully take the capacitor out from the circuit board and perform a discharge with alligator clips cables and a resistor as explained above or consult a professional HVAC specialist.

First Steps

Switch the multimeter to its resistance setting or to “Ohm.” If your device offers several options for measuring resistance, choose the high range (typically considered 20 KΩ to 200 KΩ). Connect the multimeter probes with the correct lead end from the capacitor. Red connects with the positive probe and black with the negative probe if working with a polarized capacitor.

Take the Test

The multimeter should show the resistance measurement of an open circuit. It is important to note this number. To prove the reading, it is necessary to disconnect the meter and capacitor from one another and repeat this same test a few more times. There should be consistent results with this test to show a good capacitor. If there is no change or no measurement reported on the meter, the capacitor is dead. This is the most economical method we offer on how to test a capacitor although it is not helpful in determining capacitance.

Method 3: Testing a Capacitor with an Analog Multi​meter

Using an analog multimeter will allow you to measure different aspects of the electric activity of a capacitor. An analog meter tests AVO, which is current (A), voltage (V) and resistance (O). This test is possible to perform on hole and surface mounting capacitors.

Before You Begin

As previously mentioned, it is imperative to disconnect the capacitor and discharge it entirely. Please view above the method using alligator cables and a resistor or consult with an HVAC professional.

First Steps

After you have discharged the capacitor, place the multimeter on its OHM setting. Choose the higher range if given multiple options. Locate the positive and negative leads of the capacitor to then securely connect them with the analog multimeter probes.

Take the Test

A reading should be immediately observable if the capacitor is good. With this test, the resistance will read low at first but will noticeably increase. If there is only a reading of low resistance without a gradual increase, the capacitor is shorted and will need to be replaced. It is likely that the capacitor is an open capacitor if there is no movement of the needle while the meter is set on its OHM setting. We consider the capacitor as dead in this situation and would require a replacement.


Heating, ventilation and air conditioning systems are some of the most crucial aspects of any building or home. Maintaining comfort, air quality, and interior temperature helps create a livable space without the worry of environmental fluctuations, which can easily occur in the outdoors. These systems are part of the reason we find comfort in being indoors and part of why we enjoy shelter. Considering how important these systems are to our everyday life, it is necessary to apply the proper maintenance techniques. Developing a deeper understanding of these systems can also help us find the right professional who we can trust to perform repairs as needed.

Three Basic Methods: How to Test a Capacitor

This article outlines only three basic methods describing how to test a capacitor.  This article is for professional or highly skilled users. Before beginning any kind of service on a capacitor, carefully disconnect the capacitor from the circuit board and ground/discharge it of any remaining electric current. This is a vital step. You may use a digital multimeter with capacitance setting or, conversely, you may use a digital multimeter without a capacitance setting. Finally, we suggest using an analog multimeter which will allow you to test various aspects of the capacitor such as the current, voltage, and resistance.

Any methods described above are for use only by skilled electricians, HVAC specialists, or people who have received extensive training in working with electric components. The information displayed here is not complete, and we highly suggest contacting a professional if you are at all doubtful in executing any aspect of the methods we have shared above. 

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What Is Negative Pressure And How To Fix It In My AC?

When you think of the air inside and outside your home, you likely do not consider if there is any pressure difference. While the temperature outside might feel hotter or have a difference in humidity, typically the air pressure will be the same. If, however, you have negative pressure inside your home you will see several differences and potential issues with your AC. Most of the time you can troubleshoot the issue on your own. If you cannot, it is important to give your local HVAC service provider a call.

Air pressure is what causes your ears to pop on an airplane or on a fast-moving elevator. Typically, you do not feel a difference in air pressure when you open your front door to go outside. However, there are times where your HVAC system can cause a difference in air pressure. It results in both positive and negative pressure.

If you have ever had someone claim that they have a ghost in their house because doors randomly open or strange noises happen, it's almost always due to air pressure. But how do you know when you have a change of pressure within your home? There are easy-to-identify signs - each of which indicates that you likely have negative air pressure inside the house.

Negative air pressure often is just an inconvenience or annoyance. It causes doors to swing open suddenly or it may make opening doors difficult at times (until the air pressure evens out). However, there are other times where the negative air pressure is a much more serious problem, which requires you to address the issue right away. Therefore, it is important to identify the problem at times like this, figure out what is causing it and then go about having it corrected as quickly as possible.

Defining Negative Pressure

negative pressure where the air pressure within your home is lower than what is found on the outside

Both positive and negative air pressure can develop inside your home's HVAC system. If the air pressure is too high, the increased pressure can force doors to swing open, which becomes a safety hazard.

However, in the event of negative air pressure, it means the air pressure within your home is lower than what is found on the outside. This results in air being pulled into the house to make up for this low air pressure (in a way it creates a minor vacuum). When you have negative air pressure doors that open inward will swing open. It may even become difficult to open the door.

Now, just because you have negative air pressure inside the house does not mean the fault lies within the HVAC system. Often, this is due to other physical aspects of the building itself. However, the negative pressure does directly impact how the HVAC functions, which is why it is important to look into the problem and determine what is causing the issue to have it properly fixed.

Causes of Negative Pressure

negative pressure where the air pressure within your home is lower than what is found on the outside

There are several potential causes behind why you have negative air pressure. First, if you live in an apartment or condo, it is possible you are experiencing this shift in air pressure because of warm air rising within your building.

If your home uses an old furnace or fireplace, both devices pull in hot air through the vents. If the pressure becomes too much, it will generate negative air pressure inside the house.

Apart from using furnaces or fireplaces, an exhaust fan may pull too much air out, resulting in the negative air pressure. This is usually not an issue unless you run a large exhaust fan in your kitchen. The problem with this is it can become dangerous around open flames. So if you are experiencing this negative pressure inside the kitchen, it is crucial that you look into getting the issue fixed immediately. Otherwise, the shift in air pressure may lead to gas explosions around the stove top (particularly if you have a gas or propane stove, not electric).

If the ducts and ventilation system around the house leak, the HVAC configuration may pull in unwanted air into the vents. This may cause the creation of negative air pressure. Combine more than one of these issues together and it may lead to a substantial air pressure problem.

If you have a negative air pressure problem, it puts additional strain on the entire HVAC system of your house. This means that both your furnace and AC work extra hard to heat and cool your home to a desired temperature. The additional strain on your HVAC system reduces the life of all appliances involved. It also increases energy consumption which, in turn, will cause you to pay substantially more on your monthly utility bills. By correcting the negative air pressure problem, you will improve energy efficiency and save money on your monthly finances.


How To Fix The Problem

Most times, the negative pressure inside your home can be corrected. However, if you live in a condo, apartment or any other high-rise building, there is a chance that you cannot do much about it. The change in air pressure comes from the rising warm air. So, unless the property owner installs new insulation throughout (especially between floors), the problem will remain. In most other cases though, you can correct negative air pressure inside your home.

First, you need to have your ventilation system inspected. Cracks within the vents pull in air, potentially leading to this problem. Some cracks you will identify on your own. However, it is often best to bring in an HVAC contractor and have them inspect the entire system. This way, they can not only identify and correct the cracks in the vents, but they can find other potential issues with your HVAC system.

There are times the fan motor speed within the AC is set too high. This forces the maximum amount of cold air into the room, which might be too much for the space. This can occur if you have a larger window unit that is too large for the space. When the fan is turned all the way up, it will cause negative pressure. In these instances you need to reduce the fan motor speed. This may be all you need to do to correct the negative pressure problem.

If the problem is with the exhaust fan inside the kitchen, it is crucial for you to bring in a professional and have it corrected. This is no longer just an air pressure issue but a safety concern. As the shift in air pressure may cause a shift in how carbon monoxide moves, not to mention creating backdrafts while cooking on open flames - all of which can lead to more serious problems. So, if you notice any kind of pressure problems inside the kitchen you need to stop cooking inside the kitchen and contact a service provider right away.

The same is true if there is air pressure problems around your furnace. While your furnace is closed off, the flame should not be exposed. If any kind of leakage occurs around the furnace, it increases the chance of an explosion and the creation of a backdraft. A backdraft during a fire is one of the most dangerous conditions a firefighter will face. This is because gas in the air will surge and push flames quickly through an opening.

When you bring in a professional to service your HVAC system, the contractor will have tools on hand designed to help them pinpoint the exact cause of the negative air pressure problem. If the issue is with the HVAC equipment itself, the technician will identify the issue and go about correcting it. If, however, the air pressure issue is with something else in the house, they may not directly identify it. In the instance where the cause of the negative air pressure is not the HVAC system, it is more than likely caused by the rising of air inside the house. To see if there is a way to correct these problems, you will need to bring in a home contractor.


Negative air pressure inside your home is often an inconvenience and mild annoyance that can get worse if not corrected. It forces doors to swing open involuntarily and may make certain doors difficult to open at times. However, if you are experiencing negative air pressure inside the house, it is important for you to do what you can and correct the problem as soon as possible. This may be as easy as turning down the fan inside a window AC unit or fixing leaks within your vents. Doing both of these things will also simultaneously reduce energy consumption and save you money on your monthly utility bills. In the most extreme situations, negative air pressure becomes dangerous and can put everyone inside the house at risk. Should you run into a negative air pressure problem, it is imperative that you call a professional to find out the cause and correct it right away. If they cannot fix the problem, they will more than likely refer you to the right person for the job.

Find your best training for a job in HVAC

With the never ending change in technology, an HVAC technician should never stop training.HVAC — heating, ventilation, and air conditioning — is a career that keeps changing and growing, but never stops needing more qualified professionals. It’s well worth planning your course for a career in this enduring field.

Technical school covers the basics

Most HVAC professionals today begin with studies at a technical school, either local or online. There, they cover such basics as:

* principles of heat transfer
* fundamentals of refrigeration and electricity
* residential refrigeration and heating systems
* heat pumps
* advanced air conditioning controls
* air conditioning and heating system design
* air conditioning and heating duct design

< h2 >Apprenticeships are essential< /h2 >
A good apprenticeship is where you do real work under close supervision by a seasoned professional. The people who supervise apprentices know that the only way you are going to learn effectively is to get your own hands on the job. In an apprenticeship, good supervisors will:

* Drill apprentices on safety procedures and safety practices.
* Let apprentices try to apply their classroom learning with questions about how a situation should be handled.
* Let apprentices watch how the supervisor works.
* Let apprentices imitate the supervisor’s skills.

The cycle of thinking-watching-imitating will repeat until the supervisor is confident in the apprentice.

< h2 >Certifications: Essential and optional < /h2 >
The HVAC industry hires many employees without professional certifications. North American Technician Excellence (NATE) certifications by examination are not mandatory, but include:

* Area of service (after at least two years of service technician experience)

* Installation (after at least a year of actual real world experience)

* Senior level technician (after 5 years of work experience)

Certifications from the Environmental Protection Agency (EPA) are required because some chemicals used in refrigerants can harm the ozone layer. Four different levels are available, depending on the equipment a technician services.

< h2 >Never stop training yourself< /h2 >
Technology keeps moving forward and HVAC is no exception. Ten years ago, home systems weren’t programmable. Ten years from now, who knows what resources we’ll offer? Plan to always read every day to keep up with the field.

A career in HVAC keeps people comfortable and productive all year round. I hope you will join us in this valuable profession.

Air Conditioning Troubleshooting

Homeowners should have some air conditioning troubleshooting skills

Photo Courtesy of Wootang01 via Flickr

How does a homeowner perform air conditioning troubleshooting?

An air conditioning system, whether central or a room unit, can last for a long time if it’s well serviced. Though some things, like an annual inspection, should be left to an HVAC professional, there are many things that the homeowner can do themselves over the year to make sure their air conditioner is in good working order. Here are some things a homeowner can do if the central AC system’s not running, if it runs but isn’t cooling, if it’s cycling too often, or if the cooling is uneven. There’s also a tip for troubleshooting a room unit.

• The AC Isn’t Running At All

This might be the result of the thermostat being set incorrectly or it might be the result of no power getting to the unit. The homeowner should check to see that the power is on by checking the main power switch and the circuit breakers. They should also make sure that the temperature of the room is above the thermostat’s setting.

• The AC is Running But Isn’t Cooling The Room

The unit might need refrigerant or there’s something interfering with the air flow. The homeowner should check to see that the filters are unclogged and the blower isn’t malfunctioning. They should clear away any blockages around the condensing unit. If the unit needs refrigerant, this needs to be done by a professional.

• The System Cycles Too Much

This might also be the result of a blocked airflow or a thermostat that’s not working. The homeowner should once again check to see that the air flow isn’t impeded, then check the thermostat.

• The AC Doesn’t Cool Evenly

For a central AC this means that the duct system needs balancing, or the AC isn’t powerful enough to cool all the rooms in the house evenly.

•A Room Unit Gurgles or Drips Down the Front

This might mean that the cabinet’s outer section isn’t sloping toward the condensate drain. The homeowner should turn off the unit and make sure, with a level, that it’s sloping properly. Also, the homeowner should make sure that the condensate drain isn’t clogged.

Increasing Home Efficiency for Heating and Air Conditioning

Heating and cooling costs are one of the major expenses with most homes.

<a href="" rel="nofollow">Photo Courtesy of nickhodaly via Flickr</a>

Heating and cooling costs are one of the major expenses with most homes. However, unlike other things like mortgage payments or taxes, the amount you spend for conditioned air is something you can easily change by taking the right steps. The best way to reduce the amount you spend for conditioned air is to increase your home’s overall energy efficiency. There are many ways to go about this.

Sealing Air Leaks

One of the primary reasons that many homes lose energy is because of leaks. Cracks can allow air infiltration that lets conditioned air to seep out of your home to the outside or into unconditioned spaces such as the attic or basement. Use a lit incense stick to find leaks in your home, since the smoke from the incense will be drawn toward the leaks. Seal small cracks with caulking. Seal larger cracks or gaps around pipes or along the foundation sill with expanding foam.


Another vital thing to consider when you want to increase your home heating and cooling efficiency is your insulation. Because heat rises, the insulation in your attic is of greatest importance. This is why your attic insulation should be at least R-60, whether you use rolls or blown in loose fill. To check your wall insulation, you can turn off the power and look behind an outlet or switch plate, or you can cut a small hole you later patch. If you need more insulation in the walls, hire a professional to add loose fill or expanding foam.

Ductwork Layout

The layout of ductwork can have a major impact on how well your heating and cooling system works. If the ductwork travels through unconditioned areas, the temperature differential can draw energy out of the system. To combat this, you can redo the ductwork, which might be difficult and expensive, or you can add rigid insulation around it.

Making your home airtight is one of the best ways to make your heating and cooling system more efficient. Some aspects of this will probably require the help of a professional.

Solving Air Conditioning Problems

Learning some air conditioning troubleshooting skills will come in handy when your HVAC acts up.

Photo Courtesy of Wootang01 via Flickr

In the heat of the summer, you will definitely want your central air conditioning system to be working properly. Aside from the fact that it will help keep you and your family comfortable, it will also save you money and even protect your health. If your air conditioning system is not cooling your home as it should, there are a number of things you can look at when trying to pin down the cause.

Ductwork Leaks

The government estimates that in the average home in the United States around 20 percent of the conditioned air being pumped through ductwork is lost because of leaks. This means that the rooms will not be as comfortable as they should, and your bills will be unnecessarily high. You (or a professional) can check for leaks all along the ductwork by holding burning incense along the connections. Any movement in the smoke indicates a leak that should be sealed with mastic.


The filters in central air conditioning systems should be replaced or cleaned, depending on the type you use, every month or two. Otherwise, the airflow through your system can be reduced.

Return Air Ducts

If you find that the upper floors are not cooling sufficiently, it may be that your return air ducts are not functioning properly. The air return ducts carry the hot air from the second floor back down so it can be cooled. Make sure that they are installed in the correct location, which is near the ceiling. Ensure that nothing is blocking them.

Compressor Maintenance

There are several things that can go wrong with the outside compressor unit that might make your system less effective. However, most of these problems are best handled by a professional. For example, dirty coils or lower refrigerant pressure could both reduce the effectiveness of your system.

Finding the reason why your central air conditioning system is not performing as well as you would like usually requires a careful examination of the entire system. However, this is often the only way to zero in on the problem or problems.

How to Choose a HVAC Professional

Have your HVAC system installed or fixed only by a qualified HVAC professional

Photo Courtesy of Alin S via Flickr

Whether you want to install a new HVAC system, repair your current one or simply want to purchase a maintenance agreement, you should make sure that the company you hire has the knowledge, tools and experience you need. In other words, you need to know that they are true professionals. There are many individuals that will pretend to be experienced with HVAC installation or repair, but many of these are merely weekend experts who have questionable skills and who use second-rate parts. There are several things to look for when choosing your HVAC professional.

State Requirements

Learn what the licensing requirements are in your state for HVAC technicians and find out if the company you are considering meets the requirements and has been licensed. Also, find out if the state requires insurance and bonding.


Ask the company if it can offer you references. If they take offense, move on to the next company. If they do offer references, call the references and ask about the quality of the service they received.


Ask the company if they give printed estimates for all work. Having a written estimate before work is done protects you from “surprises.” Any professional should be willing to do this.


Most states have a way for customers to lodge complaints against contactors. Check with the state to learn if there are complaints against a contractor you are considering and what the nature of the complaints are.

Employee Background Checks

In recent years there have been a number of cases in which criminals have sought employment with HVAC companies for the purpose of gaining access to homes. For this reason, you should confirm that any HVAC contractor you hire performs full background checks on its employees.

Given the number of amateurs out there pretending to be HVAC experts, if you are going to protect yourself and your investment you should ensure that the people you hire are fully qualified to do the work. Doing this requires a bit of research, but the peace of mind you will get will make it well worth the effort.