A/C Help

[WillB]

Noticed last week my A/C stopped blowing cold and the compressor is not coming on. Truck is a 99 GMC k3500 OBS. So far I have done the following. Checked pressure at the compressor and it checked fine. Checked the fuse, also checked fine. Tried jumping low pressure switch. Compressor does not come on. I have power at the green wire at the low pressure switch. If I pull the relay, I can jump the relay and get the compressor to kick on. I've swapped relays and I have the same problem. Next thought is a broken wire between the low pressure switch and where ever it goes. Does it go to the PCM or to the relay/fuse block? I can't seem to find a wiring diagram that shows where it goes. Any other suggestions on what to check? Compressor, low pressure switch and in dash controls are all a year or so old.

 

[OBS_909_CHEVS]

Did you do the paperclip in clutch cycling switch on accumulator back near firewall that should force compressor to kick in if not check plugs that connect to it and the ones directly on compressor...maybe try cleaning and closing gap on clutch pulley with brake cleaner and a flat head screwdriver...could also just be low on R134a buy a lil can at O'Reilly's for like $7 plus 10 refundable deposit return when empty for money back...good luck and keep Chevy Rolling!

 

[WillB]

I have tried jumping both the low pressure and high pressure switches with no luck. I have put a gauge on it and it is good on R134A.