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Dan, Technician
Category: GM
Satisfied Customers: 23986
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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GM c5500: We have just purchased a 2006 gmc c5500 diesel 6.6

Customer Question

We have just purchased a 2006 gmc c5500 diesel 6.6 and are trying to get a wiring diagram for the air conditioning. I'm not sure if the wiring has been modified or not but there is 12v going to the compressor on the green wire but compressor won't go on. However if I put a live wire and a ground to it it goes on. Also when ac is turned off 12v stays on the green wire
Submitted: 2 years ago.
Category: GM
Expert:  Dan replied 2 years ago.
Hello, my name is ***** ***** I'm here to help get your problem solved. If AC has 12v on green wire at all times and it doesn't work but works when adding ground to black wire then it sounds like you have a bad ground. Does black wire have ground at all times?
Customer: replied 2 years ago.

Did a continuity test between black and ground-no continuity with any ac switch position. Does leading a path to grd turn this system on? I would like to try and get a wiring diagram as I think it may modified. At some point it looks like the green pwr wire and black were wired together with a diode - does that make any sense?

Expert:  Dan replied 2 years ago.

The black wire should have ground at all times. Here is wire diagram to help with testing, let me know how it goes or if you run into more questions. Thanks.



Customer: replied 2 years ago.

Kind of wondered what happened to your reply and now I see you replied days ago. Sometimes just answer doesn't notify me of a reply for some reason. Thanks for that. I will have a look and get back to you if need be otherwise I will close the file.

Expert:  Dan replied 2 years ago.
No problem, let me know how it goes. Thanks!