About two weeks ago my a/c stopped working. When I tried to service it, I discovered the clutch was not engaging. I jumpered the pressure switch plug and that didn't work. I jumpered the clutch relay and the clutch engaged. I'm getting 12-14 volts at the pressure switch plug. Checked the wiring and found some chaffed wire that were rubbing aganist the power steering pump pulley. Repaired wires and no help. Has anyone heard of the Powertrain or Engine Control Module causing the A/C not to work? It appears that I'm getting power at all the right places. The grounds seems to go through the ECM. Could the chaffed wires, one was the wire to the ECM, shorted the A/C circuit in the ECM?

 

ok i am a bit confused,, you jumped the relay and it worked.........so you are getting power in to the relay but not out ?? did you try a new relay ??

also why don't you tell us year and model it will make helping you a bit easier

did you chk fuses ?? if a/c power wire was rubbing on the pulley most likely it blew a fuse

 

1997 Civic LX.

Yes, I jumpered the relay, and the clutch engaged. You are correct that the relay is not working, but its not the relay itself. I swapped relays with the condenser fan relay, and read throught the relay with an ohm meter. I didn't buy a new one because I suspected both couldn't be bad. I guess I could buy a new relay to rule that out. You know, never say never.

Both the fuses are good. I'm getting 14v at the pressure switch which means the fuse under the dash is good. and I'm getting 14v at the clutch relay which means the fuse under the hood is good.

The wire that was rubbing was the blu/red wire that goes from the pressure switch to the ECM not the hot wire (blu/wht) to the fuse.

Thanks!!!

 

ok amigo follow these directions
first off.. chk fuse # 56 20 amps in the underhood fuse box,chk fuse # 17 , 7.5 amps in the underdash fuse box
if a bad fuse replace and retry

if both fuses are ok

you need to chk for power at blk/yeallow wire going into the relay and for ground at the blk/red wire...

which wires did you jump at relay to make compressor come on ??

when you turn the system on you should habve ground at the blue/white at the pressure switch and if switch is good you should also have ground at the blue/red coming out of the pressure switch,, than that wir turns color before it goes into the realy to blk/red

so if you do not have ground at those wires relay will not engage . so do not replace anything till you properly diagnose it

try something.. after you chk the fuses, ground the blue/red wire at pressure switch, if system comes on,, you got a problem downstream with ground circuit could be the thermostatic switch ..
chk those and report the results

 

same thing happened to me and it was, in fact the 20 amp fuse (56)

 

Unfortunally, this time doesn't seem to that easy. Both fuses are good. Also, I've run out of time to work on my problem until the weekend. I'll continue t/sing and let you know. Thanks so much for your ideas.