A/C What are these switches

mytrplseven · mytrplseven's Garage

It's A/C time!! Thought I had damaged condenser because of a bunch of dented fins on the bottom. I was going to remove it when I disconnected the bottom line and SPLAT, green tracer stuff under pressure blew out of the fitting. Sooo, it appears that there was no leak after all. Now I'm getting ready to take the car to the a/c shop for service and I realized that the compressor won't engage because of NO pressure in the system, but in looking around I found these two switches on the line connected to the receiver/drier.

What are these switches and why doesn't the one on the top (see arrow) show up on other pictures I've seen of this part of the system? And yes, there are wires connected to the bottom switch.

kdjones2000 · kdjones2000's Garage

One is a pressure switch, and I believe the other is a temperature switch.

Compressor will not engage until a minimum pressure is in the system, in order to protect the compressor.

I assume that the other will kill the compressor if the temperature of the refrigerant going into the condenser gets too high.

Pauld_94S2 · 09-17-2018, 12:36 PM

kdjones2000 is almost correct: "One is a pressure switch, and I believe the other is a temperature switch."

Both are pressure switches.

The green one is the high pressure switch, shuts off compressor if condensor pressure is too high.

The black one is low pressure and turns off the compressor if refrigerant is low or empty in the system.
If you short the two wire connectors together, the compressor will run. That's what can be done to get the compressor running so refrigerant can be added to the system.