Troubleshooting common air conditioning problems

If the problem still exists after doing some basic troubleshooting, call an HVAC contractor for professional help.

If the problem still exists after doing some basic troubleshooting, call an HVAC contractor for professional help.

When temperatures soar and your air conditioning unit decides to stop working, you need a quick solution. While many air conditioning repairs require a professional, homeowners can troubleshoot some common home A/C problems themselves.

Air Condenser Isn't Running

If your condenser isn't running, check the power to make sure the unit is plugged in. If so, check for a blown fuse or tripped circuit breaker. Restore the power and see if it starts.

Another potential cause is a thermostat that isn't set properly. Lower the thermostat by five degrees and see if it kicks on. If not, the problem is likely a faulty motor or compressor — a problem that will require professional help.

Inadequate Air Cooling

If the central air conditioning unit doesn't seem to be cooling your home adequately, start by lowering the thermostat five degrees. If that does not fix the problem, you may have a dirty evaporator. Carefully clean the evaporator and let it run for a few hours. If the problem remains, it could mean you have an improperly sized air conditioner.

If you pair your zoned system with programmable thermostats, you could save up to 30 percent more on heating and cooling costs. (Photo courtesy of Air Treatment Inc.)

Keep in mind that an extremely hot day may impact your unit's effectiveness. If temperatures outside are over 100 degrees, you may not be able to achieve 62 degrees inside your home, especially if you have a lot of windows letting in the sun's energy. Always consult with a professional before making the decision to replace your unit, especially if temperatures have been unusually high.

Air Unit Runs but Doesn't Cool

If your A/C is running but you don't feel any cool air, you should still check the thermostat. Next, take a look at the condenser. Is it dirty or blocked? If so, clean it and remove the blockage. The condenser can become blocked by tall weeds, grass or other airborne debris.

It could also be the result of a faulty compressor, or an inadequate amount of refrigerant in the system. Again, these are problems that a professional needs to address.

Air Unit Shuts On and Off Repeatedly

This is another problem that can happen with a dirty or blocked condenser unit, as well as a dirty evaporator. Most of the time, giving the entire unit a good cleaning and removing any obstructions will eliminate the problem.

When to Call a HVAC Professional

Cleaning your air conditioner is something you can do on your own, provided you have a basic understanding of the parts of the unit. But any time you need to address the coolant, you need the help of a professional HVAC contractor. If you've already done some basic troubleshooting and the problem still exists, you need to call an HVAC contractor.

This is an updated version of a story originally posted on Sept. 20, 2012.

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Tips for Troubleshooting Window Air Conditioner Problems


window A/C (Photo by window A/C)
Call an HVAC technician if you have difficulty troubleshooting problems with your window air conditioner. (Photo courtesy of Angie's List member Charlia E. of New York) (Photo by window A/C)

If you have a window air conditioner that's not cooling or working properly, these troubleshooting tips can help narrow down possible causes of the A/C problem.


house too hot in afternoon.10 degree difference outside .78 inside set on 74. 88 degrees outside

My A/C unit is thumping when it shuts off. I think it has been over charged. Is this the problem and what should I do about it?

The compressor of the outside unit does not work. But the inside air is running cool

Why is my ac unit dosent turn off I can see my condenser unit turn off and on but unit inside stays on all the time even if i turn it off

My air conditioning outside unit beeping when turn on heating. I did not try turn on cooling, cause is still cold. Thank you in advance for answer.

my AC is working and everything is functioning but not blowing cold air as required, what could be the problem?

Hi, my 48000btu cassette air con compressor is not running. we have changed compressor and pcb but keeps flashing for a faulty.What could be my problem?

I have black sut all around my air vents what could be the cause of this.

Hi, my central heater sometimes works and sometimes doesnt. Lets say I set the thermostat to 70 deg (auto). Sometimes even if it gets too cold and the temp is showing in the lower 60 deg, the heater will sometimes come on but sometimes it wouldnt. I can swithc the terminal to fan/on and it will blow air (not heated) but when I switch to "auto" hoping heater will come on, it doesnt even blow any air.

just want to know why the circuit breaker always trip after turning on the ac for several minutes

i hear it that is on but there's no air coming out of the vents

My home air conditioner works, but it doesn't blow cold air as strong as needed. What should I do?

Hi Alex, Katie from Angie's List here. See the article's section above on the unit running but not blowing cool air. But remember, an A/C professional can help diagnose and fix all air-conditioning realted issues! Find a highly rated provider in your area here:

The technician told me that there is air in the compressor line which causes the unit to have an erratic performance. The solution would be to replace the Freon with a new batch. The cost would be $350.00. Frankly, I've never heard of such a thing. Can anybody help me out?

If Freon is leaking, that generally means you have a line leak that needs to be addressed. You might want to get a second opinion, and learn more info from these two articles: and

i just want to ask question about my window type aircon. when the compresor is working the cooling is normal but it takes to 2 to 3 minutes only and then compresor stop. it will start again after 7 to 8 minutes. Can you help me please to determine what problem i have to my window type aircon? Thank you and more power..

The inside blower fan runs intermittently in the ON position and the COOL position but seems to run continuos in the HEAT position. Will a faulty run capacitor works intermittently?

My AC doesn't shutdown through its remote. when i power on the main supply, its motor automatically starts and wind blows. when i press the power on switch of the remote the swing opens and cooling starts. when i power off the switch from remote, the swing stops but the motor doesn't.

the air handler where the main filter is dips most of the time recently--any ideas how to fix

what would couse the motor this is are 3 one. we put a new control board 7/10/13. we the new motor on

Made a loud noise and it shut off.

Often the problem can be from a dirty air filter. If the filter is clogged, there will be a reduction in the air flow.

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