What is an AC high-pressure switch?
Your car has two air conditioning pressure switches—a low-pressure switch and a high-pressure switch. Both work together to communicate refrigerant pressure with the compressor. If the pressure gets too high, the high-pressure switch signals to the compressor to shut off power.
The AC high-pressure switch looks like a small knob mounted to the compressor’s high-pressure side. The switch also monitors blockages in the AC system that can cause pressure to build up. It might be a small part, but it’s vital to your car’s AC!
How do I know if my AC high-pressure switch is bad?
It can be hard to distinguish problems with the high-pressure switch and the low-pressure switch, but here are common signs that you’re dealing with a bad AC pressure switch:
AC turns on and off rapidly: The high- and low-pressure switches work together to send signals to the compressor, so if the high-pressure switch doesn’t work, your AC might cycle on and off more frequently.
AC doesn’t blow cold air: If the high-pressure switch is broken, the AC won’t work at all. When you switch on the AC, you’ll just get hot air blowing in your face.
Compressor doesn’t come 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.
Loud or strange noises: The air conditioning unit usually operates silently, so if you hear any unusual sounds like clicking or humming, get your AC inspected immediately. These noises might mean that refrigerant pressure is building up.
How often should a high-pressure switch be replaced?
AC pressure switches last up to 50,000 cycles, which means turning the system on and running it for about 20 minutes). Most drivers find that a new switch will last the life of their vehicle. You only have to replace the high pressure switch if it’s damaged or malfunctioning.
Keep in mind: AC switches are not inspected during routine maintenance visits. If you’d like a mechanic to give your AC system a check-up, ask them to look at the high pressure switch, too.
Can I replace the AC high-pressure switch myself?
Replacing the switch isn’t complicated, but you do have to disconnect the battery, and you’ve got to be confident that the high-pressure switch is the culprit. If you’re having trouble pinpointing the problem with the AC, get a professional inspection since the issue could be with the blower, AC hoses, compressor, condenser, or evaporator.