A/C: Compressor won't kick on
Thread Starter
Drifting
Joined: Feb 2015
Posts: 1,440
Likes: 1,031
From: Baton Rouge Louisiana
So if the PCM isn't grounding out my relay to engage my AC compressor, then something must be telling it not to, right? I'm not getting any codes for this, but do you think the pressure switch could be giving a bad signal to the PCM? Or could my head unit be bad?
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
Don't forget to do the following when the ignition is ON.
I would make sure you actually have voltage at the relay 34 coil. If so, then make sure the wire to the PCM is good and not open.
If no power at relay 34 coil then check out relay 42 which powers 34. It may not be getting power or have a good ground. Don't forget Engine fuse box fuse 24 in between may be an issue.
If you don't find anything there then I would replace the pressure switch and then go from there.
If you need any help with the circuit diagnostics PM me with your number and we can discuss.
Here is the schematic and the PCM pin outs.
https://www.dropbox.com/s/c3b55i76mz...ystem.pdf?dl=0
https://www.dropbox.com/s/s1qllv99u2...Views.pdf?dl=0
Mr. Sam
PS: I find using a small paperclip straightened out fits into a relay terminal perfectly. Most Multimeter probes are just too big to fit.
I would make sure you actually have voltage at the relay 34 coil. If so, then make sure the wire to the PCM is good and not open.
If no power at relay 34 coil then check out relay 42 which powers 34. It may not be getting power or have a good ground. Don't forget Engine fuse box fuse 24 in between may be an issue.
If you don't find anything there then I would replace the pressure switch and then go from there.
If you need any help with the circuit diagnostics PM me with your number and we can discuss.
Here is the schematic and the PCM pin outs.
https://www.dropbox.com/s/c3b55i76mz...ystem.pdf?dl=0
https://www.dropbox.com/s/s1qllv99u2...Views.pdf?dl=0
Mr. Sam
PS: I find using a small paperclip straightened out fits into a relay terminal perfectly. Most Multimeter probes are just too big to fit.
Last edited by dadaroo; Jul 7, 2015 at 08:24 AM.
