Air Conditioner wiring diagrams

Tiny
KURT_S_37
  • MEMBER
  • 2003 CHEVROLET TAHOE
  • V8
  • 4WD
  • AUTOMATIC
Need AC Wiring Diagram for 2003 Chevy Tahoe Compressor not cycling.
Has refrigerant. Need to troubleshoot the control circuitry.
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Monday, July 18th, 2011 AT 4:52 PM

9 Replies

Tiny
JDL
  • EXPERT
At the compressor relay, terminal 30 is hot/voltage all the time. Terminal 86 goes hot with the key on. Terminal 85 is ground for the coil side of relay, controlled by the pcm. When the relay is energized, that line with the arrowhead, moves to terminal 87, that circuit carries voltage to ac compressor. At the ac compressor, dark green wire is voltage, black is ground. You have to have both.

You might be ahead to check for hvac trouble codes. Might need to know the pressures on the gauges. The low and high side have sensors that can keep the compressor from engaging. The high side sensor is on the high side hose in between the evaporator and condenser. Jump across the 2 wire sensor to see if the clutch engages

Here is a wiring test guide

https://www.2carpros.com/articles/how-to-check-wiring

Here are the wiring diagrams for the air conditioner system to the automatic and manual.

Check out the diagrams (Below)

Please let us know if you need anything else to get the problem fixed.

Cheers
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+6
Monday, July 18th, 2011 AT 7:49 PM
Tiny
KURT_S_37
  • MEMBER
By passed the pressure switches first thing. Still no compressor engagement. Will proceed with further troubleshooting this evening with the info gathered from here, and elsewhere on the web, and get back to you with further queries, or, (hopefully) resolution of my problem.

Thank you for your quick response
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+4
Monday, July 18th, 2011 AT 9:00 PM
Tiny
JDL
  • EXPERT
Let everybody know what you find.
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+1
Monday, July 18th, 2011 AT 9:06 PM
Tiny
KURT_S_37
  • MEMBER
Finally got to do some more testing on the Tahoe A/C system.
(My daughter-in-law drives it and between work, school and three teenage granddaughters, it spends most of its time on the road. )

Was able to verify clutch operation and wiring to the underhood relay.
Triggering the relay with a lead connected to 12-v brings the compressor on line and the system starts cooling.

Still cannot get a signal on the control line from the interior.
(This with the pressure switch bypassed. - Btw, I checked the pressure switch with a meter and it tests good.)

Looks like I still need a diagram of the control circuitry in the dash.

This Tahoe does not have the 'Climate Control' version, it is the manual control system.
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Thursday, July 28th, 2011 AT 3:50 PM
Tiny
JDL
  • EXPERT
Here you go, below. The computer grounds the coil side of ac clutch relay. Did you check the relay itself?
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Thursday, July 28th, 2011 AT 6:11 PM
Tiny
KURT_S_37
  • MEMBER
Thank you sir!

Need clarification on connector B3. Image split through that one with no color or function visible on the second part. So I replaced the relay and the compressor kicked on. Do you think the compressor coil is drawing too much amperage?
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Thursday, July 28th, 2011 AT 8:33 PM
Tiny
JDL
  • EXPERT
It is possible for sure here are two guides to help you see what you are in for when changing the compressor out.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

and

https://www.2carpros.com/articles/replace-air-conditioner-compressor

Please let us know what happens.

Cheers
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Thursday, July 28th, 2011 AT 8:46 PM
Tiny
KURT_S_37
  • MEMBER
Yep, I replaced the relay and it worked I think I will let it run for a bit before I change the compressor out thanks for your time this site is great!
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Thursday, July 28th, 2011 AT 10:02 PM
Tiny
JDL
  • EXPERT
Nice work, we are here to help, please use 2CarPros anytime.

Cheers
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Friday, July 29th, 2011 AT 5:22 PM

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