Common Air Conditioner Problems & How to Fix Them 

There are a lot of things that could go wrong with your heating and cooling system, but there are also a lot of things you can do to stop them. If you keep your system in good shape and do routine maintenance on it on a regular basis, you shouldn’t have any trouble using your air conditioning. 


If you smell something bad, it’s time to clean or replace the air filters. If your filter is dirty or clogged, it won’t let the right amount of air flow through your system. This can cause mold to grow. Mold will also grow if your system doesn’t get enough airflow and moisture can’t evaporate out of it properly. 

To reduce odors in your home: 

Every month, clean or change the filters in your furnace or air conditioner. This will keep dust out so it doesn’t go back and forth through your home, which could make it smell bad and cause allergy problems for some people. 

During the winter, if you have a humidifier running inside, you might want to turn off the drain valve. Mold grows best in places with a lot of moisture. Use a dehumidifier if you notice that humidity levels are getting too high near water sources like showers or kitchens (where water vapor from cooking may collect). 

Clogged air filters 

Look at the filter. Change it if it’s dirty. Most homes should change their air filters every one to two months. If you have pets or other things that cause allergies, you may want to change them more often. You can check your filter by opening the box and seeing how much dust is on it. If there is a lot of dust, you should get a new one. 

Switch out the air filter. You can find replacement filters at any hardware store or online; just make sure to buy one that fits your unit first. 

Frozen evaporator coils 

The most important part of your air conditioner is the part that cools the air. It’s what makes the air cool, so if it freezes up while the air conditioner is running, you’ll have problems. 

Follow these steps to get rid of ice that has formed on your evaporator coils so that it can work properly again: 

Unplug the device and turn off any switches that have to do with it. You should do this even if your coils are frozen because they will probably be hot enough to start a fire if they are still connected. 

Take off all the insulation around the unit. If you need to, use a dry rag (a wet rag could cause damage). This will help you and any metal parts that are exposed thaw out faster (like those used for refrigerant lines). 

Let everything thaw for at least 24 hours before plugging it back in and turning it on again. If you can, give it more time, since there may still be ice inside that will cause problems once things start working normally again. 

Drainage problems 

Drainage problems happen often and are easy to avoid. The main cause of drainage problems is when dirt and other debris build up in the condensate pan of your air conditioner. This causes water to back up or overflow because of clogs in the drain line. 

Make sure you clean out your AC’s condensate pan often to stop this from happening (at least once a year). It’s also important to keep the blowers of your AC free of dust that could get into the filters and stop air from moving through them. 

Malfunctioning capacitor 

A capacitor is a piece of equipment that stores electricity. A capacitor can fail in one of two ways: it can either let too much electricity through its connections or not enough. When this happens, your air conditioner won’t heat or cool as well as it should. 

If you think that a bad capacitor may have hurt your air conditioner’s compressor, replace it with a part made by the same company that made the old one (i.e., make sure to choose an 80-amp replacement if you have an 80-amp appliance). 

Thermostat trouble 

Your air conditioner’s brain is the thermostat. It tells the unit when to turn on and when to turn off. So, if your thermostat doesn’t work right, it can give you a lot of trouble. If it doesn’t work at all, you won’t be able to use your air conditioner at all. 

A thermostat can cause problems in a few different ways: 

If it’s not working at all, nothing will happen when you push the buttons (or maybe even if you don’t). 

If one part of your thermostat breaks (for example, if the display doesn’t work), some functions may still work while others don’t. However, this is usually a problem that needs to be fixed by a professional, since there may be other parts that have also broken and need to be replaced, and because it can be dangerous to use complex electronic devices when you don’t know what’s wrong with them. 

If one part has stopped working but another part is still working well enough for most people’s needs (for example, if only half of an LCD screen is lit), there may be ways around this problem, depending on what went wrong. 

Again, these kinds of problems should usually only be fixed by professionals, unless they’re very simple problems like needing new batteries or something similar, which could be easily fixed by an amateur handyman or handywoman like yourself. 


We hope this list of common problems with air conditioners was helpful. If you’re still having problems with your AC, don’t be afraid to call a professional air conditioning repair service who can help you figure out what’s wrong and fix it.  

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