What is an AC pressure switch?
A pressure switch is also called a pressure sensor. Your car’s AC has low pressure and high pressure switches that work together to signal refrigerant levels to the compressor. They protect the compressor if the pressure levels are too high or low.
Both of the switches look like small knobs and they’re mounted directly on the compressor. The high pressure switch alerts the compressor of high refrigerant pressure and blockages in the system. The low pressure switch turns off power to the compressor if refrigerant levels are too low to operate correctly.
Both switches are responsible for making the air conditioning system run smoothly
How do I know if my AC pressure switch is bad?
If either switch isn’t working, they’ll typically display the same signs. Here’s what to look for:
AC cycles on and off rapidly: The AC will turn off and on more frequently if one of the pressure switches isn’t doing its job.
AC doesn’t blow cold air: If one of the switches isn’t communicating accurate pressure readings to the compressor, the system can’t make cold air.
AC compressor doesn’t turn on: A broken high pressure switch won’t signal high pressure to the compressor, so the compressor won’t properly pump refrigerant through the system to cool your car. If the low pressure switch is damaged, the compressor could break.
Loud or strange noises: Your AC shouldn’t make any noise if it’s working correctly. If you hear any unusual sounds like clicking or humming, get your AC inspected immediately. These noises could mean that refrigerant pressure is building up.
How often should a pressure switch be replaced?
Pressure switches usually last the life of the vehicle unless a switch malfunctions or gets damaged. Specifically, a pressure switch lasts for 50,000 cycles (turning the system on and running it for about 20 minutes). You only need to replace the switch if it stops working.
Can I replace a pressure switch myself?
If you’re comfortable working on your car’s electronics and disconnecting the battery, you should find replacing a pressure switch pretty easy. It’s actually harder to diagnose the exact problem with an AC unit, since it’s an intricate closed-loop system.
AC problems can be caused by any number of components like a malfunctioning compressor, evaporator, condenser, or blower motor for instance. If you’re not one-hundred percent sure that a pressure switch is bad (and you can identify which one needs to be replaced), get a professional diagnosis.