Unlock the Right Part
for Your Repair
Find the exact part you need
Enter your model number to see parts that fit your machine.
Order by 2:00 a.m., and we'll ship the same day
Price Match Guarantee
Order by 2:00 a.m., and we'll ship the same dayChoose Product
Identify Problem
03
Find Solutions
HomeRepair HelpA/C RepairAir conditioner compressor won't run Repair
My AC Compressor's Not Turning On
If your air conditioner compressor won’t run, the unit may still power up and even run the fan, but it will not cool properly because the compressor is not starting. The most likely cause is a failed temperature control thermostat, which can have burned electrical contacts that stop power from reaching the compressor motor. Next, check the temperature control board, since it supplies voltage to the fan motor and compressor, but confirm the overload, capacitor, and compressor first before replacing a board. A defective thermostat can also keep the compressor from turning on, while a burned-out overload may interrupt power to protect the compressor from excessive current. The compressor itself can fail, but that is less common and should usually be handled by a licensed technician. A faulty thermistor can also cause an AC compressor not turning on if it cannot properly sense air temperature. Enter your model number on RepairClinic.com to find the exact temperature control thermostat, control board, overload, compressor, thermistor, or other replacement part made for your specific air conditioner.
01 - Air Conditioner Temperature Control Thermostat
The temperature control thermostat has electrical contacts inside that burn out over time. It is possible for the thermostat to still turn on the fan motor but not the compressor motor.
Enter model number to search for the required part specific to your product
Highly Likely
02 - Air Conditioner Temperature Control Board
The temperature control board provides voltage to the fan motor and compressor. If the control board is defective, it may stop providing voltage to the compressor. Control boards are often misdiagnosed. Before replacing the temperature control board, make sure you check more commonly defective parts—particularly the compressor overload, capacitor and the compressor itself. If you are certain that all of the other components are working properly, replace the temperature control board.
Highly Likely
03 - Air Conditioner Thermostat
The thermostat monitors the temperature of the air. When the air temperature rises above a set point, the thermostat activates a switch to provide power to the fan and compressor. If the thermostat is defective, it may prevent the compressor from running. If you determine that the compressor is at fault, replace it.
Highly Likely
04 - Air Conditioner Overload
The overload protects the compressor from burning out if it draws too much current. Over time, the overload can burn out. To determine if the overload is burned out, use a multimeter to test the overload for continuity. If the overload does not have continuity, replace it.
Highly Likely
05 - Air Conditioner Compressor
The compressor itself might be defective. However, this is not usually the case. Before replacing the compressor, be sure to check more commonly defective components—particularly the overload protector and the compressor capacitor. If the compressor is defective, it should only be replaced by a licensed technician.
Highly Likely
06 - Air Conditioner Thermistor
The thermistor is a sensor connected to the control board that detects the temperature of the outside air. If the thermistor does not have continuity, it can prevent the compressor from running. To determine if the thermistor is at fault, use a multimeter to test it for continuity. If the thermistor does not have continuity, replace it.
Common
07 - Air Conditioner Relay Board
The relay board provides voltage to many of the components of the air conditioner. If the board is defective, it can stop sending voltage to the compressor. Relay boards are often misdiagnosed; before replacing the board, make sure you check more commonly defective parts—particularly the overload protector, the compressor capacitor, and the compressor itself. If you are certain that all of the other components are working properly, replace the relay board.
Common
Frequently Asked Questions
Why is my air conditioner compressor not turning on but the fan still runs?
Can a bad thermostat or thermistor cause my AC compressor not to turn on?
How do I test the compressor overload when my air conditioner compressor won't run?
Should I replace the control board if my AC compressor is not working?
How do I find the right replacement part for an air conditioner compressor not starting?