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Why My AC Compressor is not Working?

If you find that your air conditioner isn’t working at all, the system’s compressor could be to blame. Many of these issues are quite complicated and require professional assistance. But, it’s important to pinpoint what could be the problem.

Air Conditioner Close Up

What Is an AC Compressor?

The compressor is typically located in the outdoor unit. The compressor’s main function is to compress cool, low-pressure, gaseous refrigerant until it is hotter and has achieved a higher pressure. From there, the gaseous refrigerant is squeezed into the condenser. When the refrigerant is still in the compressor, it is considered to be at the beginning of the air conditioning cycle. If the AC compressor won’t turn on, the process of cooling can’t begin.

Check Your AC Unit For Power

While this might seem obvious, the first thing you should check is that your unit is receiving power. Check fuses to see if any power has been cut or blown. If these issues occur often, call an electrician to take a look. If the fuses and breakers are fine, call your HVAC technician.


When your HVAC technician comes to your house, they may troubleshoot some issues by checking these parts of your unit:

  • Capacitors: Often times compressor problems are caused by faulty or broken capacitors. The only way to really test if a capacitor is broken is to replace it and test it out.
  • Start Relays: Similar to the capacitor, your HVAC technician may try replacing the start relay.
  • Valves: A broken valve can cause major problems in a number of areas. One of the main problems that happen in this area, is when the refrigerant is liquid instead of gas when it reaches the compressor. If this is the case then the compressor may still run, but your house won’t be cool. Replacing a valve usually does the trick.
  • Terminal Connections: Your trusted HVAC tech will also check the terminal connections to make sure everything is in the right place and tight. A loose connection may cause your compressor to work sporadically.

Dead Compressors

If your compressor is completely dead, you can replace it with a new compressor or you can get an entirely new system. A good rule of thumb is if the replacement costs more than 50 percent of buying a new unit, it’s probably time to upgrade and buy a new air conditioner.

Call Freezing Mechanical Today

If your air conditioning is running, but not cooling, you may need a maintenance check-up.

Call us today (305) 363-7021 to schedule an annual maintenance service or emergency check-up.