Air Conditioner Compressor Not Turning On

As strange as it may sound, it is possible for your air conditioner compressor to not turn on while the fan is still working properly. “What is happening here?” you wonder.

There are several possibilities to explain the error. Each scenario has a different approach on how to fix it. To know for sure, here are the problems that you should look into:

1.   Faulty Thermostat

The first thing to check when your air conditioner compressor is not turning on is your thermostat. There are reasons for a thermostat to fail like that, but most of them are pretty easy to fix, such as weak batteries, wrong setting, or maybe it needs to get recalibrated. You may also need to turn it off and back on again to see if the problem has been resolved.

2.   Old Unit

Each AC unit will have its performance deteriorate over time. If your unit is already near its life span, then it is normal for its compressor to not work properly. If you keep using it, the system will overheat and consume more energy without giving any significant results. You will likely end up with a higher electric bill without  getting thermal comfort from your system. There is nothing you can really do to fix it other than buy a new unit as a replacement.

3.   Improper Wiring

When your indoor unit is working properly, but the outdoor unit is not  on, then maybe there is something wrong with the electrical wiring. Broken cables may cause the outdoor unit to not receive power to run. If following the wiring through the unit is too much hard work, you can just check the wiring end at the side of the outdoor unit.

4.   Mismatched Units

Although rare, sometimes people install an outdoor unit and indoor unit from different series. It usually happens when someone buys a secondhand   AC unit. Mismatched outdoor and indoor units will never work because they always work in pairs. That is why they are always sold as a package. If one of your units gets broken, you need to replace both at the same time. If you buy a secondhand system, make sure both of them are of the same model.

5.   Dirty Coils and Filters

When was the last time you got your system cleaned or comprehensively maintained? If it has been  more than six months, then you need to take a look at it, especially  its coils and filters. The dirt accumulated on them blocks the airflow, causing overheating, and forces the compressor to shut down. This problem is both easy to fix and to avoid by giving your unit a total cleanup every six months.

6.   Dead Compressor

Obviously, there is also a chance that your compressor has  broken permanently, so you will need to replace it. However, unfortunately, sometimes it is not worth replacing only the compressor because that is the most expensive part of an AC system. It may cost nearly the same as replacing the whole unit, which will perform much better than an older unit.

A normal compressor will run instantly once you turn the system on. When it doesn’t, you need to settle the problem right away before your AC overheats and develops more problems. For any doubts and difficulties, always call a professional HVAC technician to help you with them.



ECM Air Conditioning, with its headquarters located in Boynton Beach, FL, provides air conditioning services within Palm Beach County, Broward County, Martin County, and St. Lucie County. If you’re looking to have a new HVAC system installed, we’re on-call and ready to assist you. So if you’re in need of an HVAC installation, don’t hesitate to contact us today to schedule an inspection! Our HVAC installation experts will check your ductwork, measure, check wire sizes, and more before making recommendations to ensure maximum efficiency and comfort. Call us at 561-295-1763 or contact our HVAC installation team online by clicking here.


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