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3 Possible Reasons Your AC's Compressor Stopped Turning Over

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The compressor is the starting point in your central air conditioner after the thermostat has been set. Located in the condensing unit outside, the compressor takes an electrical signal from the thermostat and passes it onto capacitors then starts pumping out gas refrigerant that needs to enter the condenser coils for processing. A problem with the compressor can shut down your entire cooling system.

A compressor can also stop turning over, which means the compressor at least attempts to start things off but then nothing happens. What are some of the possible reasons your air conditioner's compressor has stopped turning over?

Broken Fan

Before you start fooling around with the compressor itself, make sure the fan in your condensing unit is spinning and at full speed when the unit is running. The fan should turn even if the compressor is turning over. If the fan isn't working, the problem could be there instead of anything with the compressor.

The fan is important to keep the temperature in the condensing unit stabilized. If the fan fails, the temperatures go up and the system shuts down as a safeguard. So what seems like your compressor turning over is actually your system overheating and shutting down.

Replace the fan and/or motor if the fan seems like the source of the problem.

Failing or Failed Start Capacitor

The compressor sends signals to a start capacitor, which gives an electrical boost to get the system going. If the start capacitor fails, the compressor can fail to fully start and then the entire system can shut down.

Are you confident in working with electricity and own a multi-meter? You can test the start capacitor yourself. Otherwise, you should call in an air conditioning services company for the test and potential capacitor replacement.

Doing your own testing? First, turn off all power to the unit via the fuse box. But you will also need to drain the start capacitor since its very purpose is to store electricity. You can do this with the multi-meter set to AC readings and with your probes attached to the terminals on the capacitor. Wait for the reading to drop to zero before proceeding.

You can now switch the meter to ohms and test again. Make sure the reading number matches what is listed on the side of the capacitor. If it doesn't, you need a new start capacitor.

Bad Compressor Wiring

The wiring on the compressor itself could also be faulty. You can conduct a visual inspection if you have experience in the area. Or, if you're fairly sure this is the problem, you can simply buy a universal compressor wiring kit and switch out the parts.

The universal kits are fairly easy to use with color-coded leads that are easy to match up with your compressor. Still, if you have any qualms handling electrical wires, you should call in a professional ac repair company. Hooking the wires up wrong could cause your compressor to die completely.

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