Why Your AC Compressor Is Not Running

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Why Your AC Compressor Is Not Running

Why Your AC Compressor Is Not Running

3 December 2017
 Categories:
, Blog


The air conditioner compressor is, basically, a large electric pump that turns the refrigerant gas into a liquid form by putting it under high pressure. This is necessary so that the refrigerant liquid can re-circulate and pick up the heat inside your house. This means your AC will not be cooling your house if the compressor is not running. Here are three possible reasons a compressor may fail to run:

There Is an Electrical Fault

The compressor is an electromechanical system, which means it has both electrical and mechanical parts. The electrical parts, mainly the motor, needs electricity to run. Therefore, if the compressor motor is not running, it might be that it has experienced an electrical malfunction or it is not getting the electricity it needs to run. If you don't have experience with electrical systems, the furthest you should go is to confirm that you have power in the house and the electrical breaker has not tripped. Further diagnosis requires professional expertise.

The Compressor Motor Oil Is Low

Your compressor may also fail to run if its motor oil is low. The compressor motor oil has three main functions:

  • It lubricates different parts of the compressor so that they don't suffer the consequences of friction
  • It helps in heat exchange by getting rid of the heat generated by the motor
  • It seals tiny openings in the compressor system so that the refrigerant doesn't escape

As you can see, the motor oil has a serious function, and its deficiency can lead to the motor's failure. This is why compressors have integrated safety mechanisms that automatically shut them down if the motor oil falls below a safe level. Note that the oil usually circulates in a closed system so if its level has fallen, it means there is a leak in the system.

High Refrigerant Pressure

High temperatures and pressures are not good for the compressor's operation. Therefore, just as there is a safety switch for low oil level, there is also a safety switch for high pressure; the switch shuts down the motor if the pressure rises to dangerous levels. Different things may lead to dangerously high pressures. For example, clogging in the condenser line, failure of the expansion valve, and damage to the compressor fan can all lead to high refrigerant pressure and compressor shut down. All these are issues that only an HVAC maintenance professional should attempt to solve. 

About Me
Understanding HVAC Issues

After years of dealing with an air conditioner and furnace that didn't work that well, I decided that I needed to dedicate some time to fixing the issue. Instead of continuing to guess, I realized that I needed to do something to fix things. I contacted a professional HVAC repairman, and he came out the next day to look over our issues. It was amazing to see how many issues he was able to resolve in under a few hours. Now, our home is comfortable and relaxing. This blog is dedicated to helping other homeowners to understand their HVAC issues and work towards resolving them.

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