Common Reasons Your Air Conditioner is Blowing Hot Air

HVAC Logo IconBy HVAC.comAugust 1, 2023

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In a previous post, one of our team members told a story of coming home at the end of the day to a soaking wet carpet caused by issues with his air conditioning system. Well, now he has another one. It is a story many people know all too well: the air conditioner is blowing hot air. And of course, it always happens on the hottest days of the summer. There are many possible causes, so let’s explore some of the most common ones.

Common causes for AC to blow hot air

Thermostat is improperly set

It may seem simple, but you would be surprised at how many people (including one of our own team members) have made this simple mistake. Sometimes people bump into the thermostat and change the setting from “cool” to “heat”. A more common mistake (and the one he made!) is changing the fan from “auto” to “on”, which causes the fan to blow air when the system isn’t running. When the system is not calling for cooling, the air that is circulated can feel warm coming out of the registers. Luckily, this is a very simple fix. Simply change the thermostat back to the desired settings and you should be cool in no time.

Restricted airflow

This is one of the most common issues that people run into when their system is not blowing out cold air. One of the leading causes of airflow being restricted is having a dirty filter. If this is the case, simply change out the filter. If you are not sure how to change your filter, check this article out. If after changing your filter you still are not receiving cold air, it may be time to have a trusted professional take a look at your system.

Electrical issues

Unfortunately, it is possible for the circuit breaker to have been tripped or a fuse to have been blown. As a result, the outside unit of your system could lose power, causing the indoor component (which is where the fan is located) to push out warm air. If this is the case, you should call a trusted HVAC contractor immediately, as this could be a sign of a serious electrical issue. Do not attempt to try to fix this yourself, as this could be very dangerous.

Refrigerant leak

It is not uncommon for refrigerant line joints and connections to come loose, causing a leak in the refrigerant. It’s also possible that if your system was not assembled properly by the manufacturer, leaks in the refrigerant could occur. There are a variety of reasons that a leak could occur. Whatever the cause may be, it is important that you get in touch with a licensed professional right away to have the leak repaired, as refrigerants can be dangerous to handle if you are not properly trained.

Dirty outside unit

Sometimes, the outside condenser unit can become covered in weeds, sticks, bushes, leaves, etc. and as a result block the airflow of your unit. This lack of airflow will result in your home not cooling properly. If you notice that your condenser is particularly dirty, it may be a good time to clean your condensing unit or call an HVAC contractor to do a tune up of your system so that you do not run into issues in the future.


If there is a problem with a compressor, the whole system will not be able to function properly. There are several possible things that could go wrong with the compressor, including electrical issues, overheating, and refrigerant issues. If your compressor goes bad, you should not try to fix it. Only a trusted professional can come out and confirm that the compressor is bad. Unfortunately, the usual outcome of a bad compressor is an expensive repair or having to replace the entire system. If you find that this happens to your system, can help.

When the heat of summer is beating down on your home, the last thing that you want your air conditioner to do is start blowing out hot air. The good news is that, in many instances, the problem can be easily resolved by you with a simple flip of a switch or change of a filter. However, if you find that the issue is something that requires a professional, get in touch with us and we will connect you with an Certified Contractor in your area that will make your home cool and comfortable again at the best value for you!

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