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How to Test an AC Pressure Sensor


Air conditioning pressure sensors, also known as AC switches, turn off a car’s air conditioning system whenever the refrigerant pressure reaches a lower extreme. This not only signals the need for a recharge of refrigerant, but also saves the compressor from running without the proper lubrication. If the AC pressure switch is bypassed, then the compressor can potentially freeze up from a lack of fluid and lubrication, requiring expensive work to be done by a professional mechanic.

Step 1

Turn your car’s air conditioning system on with the engine running. Open the doors to the vehicle, preventing the air conditioning from cycling off.