Air conditioning compressor clutch

[Matahoe]

I noticed my A/C wasn't working today. The interior fan works. I checked the underhood fuse and relay. They are working. I also jumped the always hot pin of the relay socket to the pin for the compressor clutch and the clutch engaged. Also the PCM side pin to operate the AC relay works as intended. I'm kind of stuck wondering why if everything is supposed to work, then why isn't the compressor clutch working when I put the relay back into the socket. Does the PCM check for excessive resistance or something on ac startup? Also I disconnected and jumped the pins for the high pressure switch under the hood and that didn't make any difference. Are there other fuses I need to check? Thanks.

 

[blondie70]

Don't the radiator fans come on with the AC ? Maybe , if they won't run, the AC won't work?
Good Luck with it.

 

[Matahoe]

I double checked the pin on the relay for a PCM ground signal. The PCM won't ground out the relay so that's why the relay isn't working. So looks like I need to check both high and low a/c pressure switches next. Going to take a reading of the static pressure on the low side. I got gauge with me.

 

[Fless]

You might remove the two PCM connectors and check for cleanliness. Seems to me (IIRC) the fan control contacts are in the lower part of the connector, where water can intrude and spoil things. Might be something to check.