ok I got a 2 prong switch, if your looking from the front of the vehicle it is mounted on the left hand side of the accumulator. It has gm and the part numbers 3040500 and 9042 on it. It is a female thread piece that threads onto the accumulator. The threaded piece is cracked and I need to replace it because freon is leaking out. I have did part number and name searches no luck. No part # matches. I believe it is called a low pressure switch or sensor. I am gonna go down to autozone tomorrow and I wanna make sure I get the right thing. Thanks guys. It for a 91 camaro RS 305. R-134a coolant.

 

That is a pressure cycling switch. It cycles the compresser on and off at a specific pressure. It is a pretty standard part and should be availible at any part store. You can unscrew it and take it in with you. There is a shrader valve under it that will keep freon from leaking out after it is unscrewed.

 

that is damn good to know.

 

can this switch cause freon to leak out slowly

 

Wow, this is an old post. It is possible. There is usually an O ring that goes on before the switch to prevent this.