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Air conditioner compressor not working
By the Repair.com team
Let's fix this!
If your AC system is on the fritz, you probably want the problem fixed—and pronto. Potentially, it’s the air conditioner compressor not working, and compressor replacement can be one of the more costly types of air conditioning repair. To help you determine if repair is necessary, you can perform some basic testing of the AC compressor on your own.
Locating the compressor
The compressor resembles a rounded tower and is located within the condenser unit outside your home. You will need both a flat-head and a Phillips screwdriver to remove the condenser grating and access the compressor for basic troubleshooting.
First troubleshooting steps
Before you do anything else, eliminate a disconnected power supply and improper thermostat settings as causes.
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Check your electrical panel; confirm that the circuit breaker has not tripped or the fuse has not blown.
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Check the safety switch; it should be located near the furnace. It can be accidentally shut off.
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Check the switch, breaker or fuse box located outside near the compressor unit. Check that the outside breaker has not tripped or the switch shut off.
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Check to ensure the thermostat is set to COOL, and the cooling temperature you want is less than the temperature the thermostat is registering.
Safety notice: Before working on an appliance, always shut off the power supply. This can be done by unplugging the unit from the wall outlet, removing the appropriate fuse from the fuse box, or flipping the appropriate breaker in the circuit breaker panel.
WARNING: Your AC system operates on 240 volts, which can provide a strong shock. Also, fans or motors can turn on without warning.
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Possible causes |
Signs to look for |
What to do |
|---|---|---|
Internal overload |
Is the compressor hot? WARNING: Do not touch the compressor, just hover your hand near it to feel for radiant heat. |
The compressor has an internal shutoff for thermal overload. So, if your compressor stopped working and is hot, it is likely electrically overloaded. For a compressor that continually overheats and shuts down, schedule service with a qualified AC repair professional. |
Severed, damaged or loose electrical wires |
Inspect the wires to the compressor motor. There are usually 3. Do any of them appear severed, disconnected or loose? |
Wires are connected to terminals with push-on connectors. Wiggle the connector slightly to see if it is tight. If a wire is loose, you may be able to push it back into the terminal. Repairing a wire that is severed or broken off the terminal connector is best left to those with professional electrical experience. The job requires specialized tools. |
Compressor failure |
Do you hear repeated clicking noises or a loud buzzing sound coming from the compressor? |
Have a repair expert test the condition of the compressor with a multimeter. The multimeter is a specialized tool used to troubleshoot a variety of electrical problems in household appliances. The technician will take a reading for the amount of resistance between each of the 3 wires. The resistance should be between 2-10 ohms. If any of the wires fail this test, the compressor will need replacement. |
Lack of refrigerant or bad coolant line |
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Have an AC repair expert check to see if there are any leaks in the coolant line and to add more refrigerant if necessary. Note: Repairs involving refrigerants should be performed by a qualified service professional. Refrigerants pose an environmental hazard and must be recovered from the system to meet Environmental Protection Agency (EPA) guidelines. Purchasing and replacing refrigerant requires a license. Did you know? Refrigerants such as Freon don't wear out and should never need replacing unless there is a leak in your system. Be sure any leaks are identified and fixed before more refrigerant is added or you'll simply be repeating the process later. |
Motor bad or grounded |
Is the compressor cool to the touch but not working? |
The motor may be bad (too high a resistance reading) or considered grounded (too low a resistance reading). The only way to know for sure is to test the motor using a multimeter. Have a qualified professional test the 3 compressor terminals and check the motor resistance. A failed test could mean a new compressor is needed. |
Still seeking a solution? Schedule air conditioner repair service with a qualified professional.
What to do until your AC compressor is repaired
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Make use of ceiling or portable fans to keep your home’s interior comfortable.
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Keep your drapes or curtains closed during the hottest parts of the day.
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Open windows during cooler periods (such as at night), closing them before it gets too hot outside.
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Seek relief at a public facility, such as a library, or with a friend or neighbor.
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Make your own personal AC unit. Fill 1 or more soda bottles most of the way full with water and freeze them. Once frozen, place them in front of a portable fan and enjoy the cool air.
Service pro's plea: If in doubt, stay out. Don't risk causing more damage to your product (or yourself!) by attempting to fix it on your own. It's also easier and quicker for a service technician to diagnose and fix a problem when the product is assembled. In the end, you'll save time and money.
✓ Reviewed and approved by Repair.com expert Michael & Son Services.
The Repair.com team
The Repair.com team is made up of experienced writers, editors and repair experts dedicated to providing you with the most reliable and comprehensive information about keeping your home running right.