Is your central air conditioning blowing hot air when you turn it on? While there are many reasons your air conditioner is blowing hot air, we’ll run through the most common causes that you can diagnose your HVAC repairs.

First and foremost, check your thermostat and make sure that it is correctly set. It may sound ridiculous, but sometimes homeowners incorrectly set there thermostat which will cause hot air to blow out instead.

Also, check to see if you have your thermostat set to “auto” or “on”. If it’s set to “on”, that means the fan will blow even when the air conditioner isn’t actually cooling. This causes your AC to blow out warmer air out the vents when the outside unit isn’t running.

A restriction in the airflow to and from your air conditioner often results in not enough air coming out of the vents to cool your home. Restricted airflow can also cause the compressor in your air conditioner’s outside unit to freeze up. a restriction in airflow is most like caused by a dirty air filter that has not been replaced in a long time, or dirty coils form your AC unit not having maintenance done.

It is important to recognize that your air conditioning system is made up of two main components – an outdoor unit and an indoor unit. The indoor unit houses the fan that blows air through your home, and it can only blow cool air if the outdoor unit is working. This could be a problem with your electricity. Make sure to turn your circuit breaker off before check electrical wiring, and to call a professional if you think this may the problem.

Most likely, if you’re having issues with your air conditioner blowing hot or warm air, it’s either a problem with the compressor/outside unit or your air conditioner is low on refrigerant. You may also have a return duct that is broken or disconnected and is pulling in unconditioned air from outside or an attic space. However, both of these issues require a professional’s help.

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AC Blowing Hot Air After A Power Outage

Your AC was running great, then the power flickered off and then back on during a storm. Now it is blowing warm air. What should you do? There are a couple reasons why this problem happens to more people than you would think. If you are looking for air conditioning repairs in Allentown Pennsylvania than you need to be informed on why you HVAC unit has stopped working.

Most likely, the quick off and on motion of electricity feeding the AC unit has caused the compressor to short cycle, therefore quickly overheating the compressor electrically. When the device that looks like a small silver can has had a power surge delivered to it; it has an internal short and fails to operate. It has a noticeable bulge on top where the terminals are located. This device stores energy and helps the compressor and the fan motor start. When it fails, the motor and compressor may not have enough immediate power to start and will just hum. Over a short period of time; this can be harmful to the compressor and outdoor fan motor and cause them to overheat and fail permanently. Sometimes there is no visible damage and must be tested electrically by a professional HVAC technician or electrician. Below is a picture of a burnt compressor. If your compressor looks like the one below, contact a trusted HVAC professional immediately. The capacitors can also weaken after time and become ineffective and need replacement. You might be asking yourself if this is going to damage your AC unit. In almost all cases, your AC unit will be fine, and a little overheating now and then will not cause any damage.

Burnt and pitted cap
Damaged Compressor

The next step is to turn off your AC unit and let it cool down for at least 30 minutes. This should give it enough time to cool down.


If your system does not restart after allowing to cool then make a call an experienced HVAC technician. In some cases your unit may not come back on which often indicates that there are other underlying issues that have not yet exposed themselves. These types of issues are typically identified during a preventative maintenance inspection and usually avoid costly repairs. Preventative maintenance should be performed on a semi-annual basis to ensure the longest life and least expense possible.

If your HVAC professional tells you that the failed part is a motor starting device/capacitor, ask (if your technician does not suggest it) for an Amrad Turbo-200 device and or a surge protector. The Amard capacitors are more expensive, but are of a very high quality, are made in the USA, and have a 5-year replacement warranty. The surge protector adds another layer of protection against the unwanted electrical surge that may do damage to any of your electrical components within the outdoor unit.

Amrad Turbo cap

Miscellaneous electrical problems could be the source as well. There are a ton of wires flowing in out and around the external unit and internal unit. If one of these wires is frayed, cut, or otherwise damaged, it could cause poor performance or even break the unit down entirely.

Wiring can be frayed if it gets burnt by overheating, but this is an extremely rare occurrence. Generally, wires are cut by the family pets, such as cats and dogs. If the wire is exposed and they decide to chew on it, the unit will malfunction. To prevent this from happening, you should make sure wires are not sticking out. If they are and cannot be fixed, we recommend keeping both your external and internal units protected from animals with some sort of wall or fence around it.

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Troubleshooting Your Unit

Depending on whether or not you have a central air conditioning system or a mini-split system, your initial trouble shooting will be different. Let’s look at the most popular HVAC units.

Central Air System

Central Air Unit

A clogged filter restricts airflow through the unit decreasing its efficiency and reducing the ability to effectively cool the air. If you haven’t cleaned the filter in your air conditioner recently, do it now. Filters on central AC units should be changed at least once a month, especially if your system is running constantly or you have pets.

Check the window seals around your unit to make sure hot air isn’t getting in or cold air seeping out. If so, reseal around your unit with pieces of weatherstripping.

An inspection by an HVAC technician can catch any serious problems before they get worse and leave you hot and bothered at the peak of summer. The technician will check all the moving parts as well as the refrigerant and recharge the system if necessary.

The first step in resetting your unit is to unplug it from the electrical outlet. Count to twelve and plug the unit back in. Now, locate the reset button. It should be in a visible spot, but the button may be tiny. Press it, and see if your air conditioner starts working. Try pressing the reset button once more if your unit fails to start. If you still don’t get any reaction, your next step is to flip the main circuit breaker that powers your home, and cross your fingers that it works.

Keep your air conditioner plugged in and locate the electrical panel for your house. Find the circuit breaker that controls the electrical outlet you’ve plugged your air conditioning unit into, and turn it off. Wait five minutes. Turn the circuit breaker back on and see if your air conditioner is blowing cool air. If it isn’t, try once more to reset the unit. Chances are good that this will solve your problem and get your home back to normal.

Mini-Split System

Ductless Air Mini-Split System

Start your ductless AC troubleshooting by checking the air filter. It should be washed at least every month. Also check to see if there is any ice buildup on the coil.

If there is ice build up, check to make sure the fan is working. Make sure the blower wheel is free to move. If it is free and the fan is not working then the problem is probably the motor or the control board. If the fan is working, allow the ice to melt and check the refrigerant level in the unit.

If all of the above are working, follow the same steps for the central air unit troubleshooting and unplug your unit, and reset it.