cmh1220

The vehicle in question is a 2001 C5 Z06, the problem with the air conditioning system started with intermittent A/C problems. Followed by a complete failure of the system, observation revealed that the system was properly charged but the clutch on the compressor would not engage. After measuring 13.9V at the clutch plug I discerned that the compressor clutch was bad and needing replacing. After replacing the compressor, flushing the system, replacing the condenser and properly charging with oil and 134a the system came on perfectly. However next time the vehicle was started it has begun to come on randomly. Checking the voltage at the clutch plug shows 0V when the air is off and 1.9V when on. I have tried grounding out the system in the fuse box to force the clutch on and have had no luck. Any suggestions would be greatly appreciated.

Thanks in advance!

Bill Curlee

Could be a FUSE issue, Relay Issue or even a GROUND issue. Here is the SCHEMATIC that you need:



Check the voltage at the fuse test slots on top of the fuse. Especially the PCM Fuse #16. Key must be ON as that voltage comes from the IGNITION SWITCH.

Bill

Bill Curlee

I have also seen that compressor connector/diode junction go bad. Check the connector good and make sure that the wires and diode are in good shape.

BC

cmh1220

[QUOTE=Bill Curlee;1594819782]I have also seen that compressor connector/diode junction go bad. Check the connector good and make sure that the wires and diode are in good shape.


Thanks for the reply bill, I took your suggestion and here is where I am at. I have checked the voltage at fuse #16 and #24 and it is good. I also jumped the legs of the ac clutch relay pins #30 and #87 with a paperclip and measure proper voltage there. Even with the relay jumped I am getting no voltage at the clutch plug, I opened up the diode and attempted to measure voltage before the diode and it also is not getting any power. If my relay was bad jumping it would have solved the problem? Also, I was able to pull code P1546 from the vehicle. Do you think a new relay #34 would be worth the investment?

Bill Curlee

I would check wire continuity from the relay output to Pin A on the compressor plug and pin B to chassis ground.

That will tell you if the wire is good and the ground is good. G-102 is the ground connector on the chassis frame just behind the headlight module:

It looks just like this:


That connector comes completely apart and the pins inside are WELL KNOWN to get corroded and loose continuity:

cmh1220

Good idea, I checked for continuity from the relay to the green wire of the plug and it was good, I also checked the ground wire to pin b and it had continuity. I was not however able to achieve continuity while the ground was on the car, I had to remove the ground plug from the ground behind the headlight and use the female plug b for continuity, is this normal?

cmh1220

Bill I think I solved the problem, It would seem i have a problem with my ground. I changed the ground location and the whole system sprang to life. Thank you for your help, I am new to the forum, is there a way I can leave positive feedback for you?

Black 03 Z06

Bill is a genius. Bill for President.

Honestly he knows his stuff, always impressive.

Glad you got it running again.

Bill Curlee

Not that I am aware of but, Im glad I was able to help you get it sorted out.

If that ground is bad,,,, theres a very good chance that the other one on the other side is bad also.
All of the chassis grounds are MIRROR location on the frame. Where you find one, there is one on the other side in the same location.

BC

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Engineman02

i have the same situation however I don't have power at the PCM fuse 16. I do have continuity from the ground and relay when I close it. What could cause me not to have power at the PCM?

T-RAY1978

I have a similar situation going on as well, can you explain what you did with the ground, and are you referring to the ground behind the headlight . Thanks

T-RAY1978

Nevermind I just went outside and removed the ground behind the passenger headlight, took it apart and it was corroded so I cleaned everything up and put it all back together and now my ac works again..... I have been racking my brain since it went out and was about to replace the compressor until I read this ...this forum is amazing thanks