A/C control panel wiring

uneek1976

uneek1976

G-Body Guru
Jul 24, 2009
603
41
28
Sugar Grove IL/ Chicago
#1
I'm wiring in a/c into my pcm and I'm trying to figure out which wire to use from the heater control panel as the a/c signal wire for the pcm to activate the compressor?

Please help!
 
Ribbedroof

Ribbedroof

Comic Book Super Hero
Supporting Member
Jan 4, 2009
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Wellston, OK
#2
Typically, GM used one side of the clutch cycling switch to send the A/C request signal.

This is for an LT engine, but should give you some direction

http://www.goldsswagon.com/diagrams/impala_manual_ac.pdf

You could also just let the car's control head run the compressor, it has been written that the pcm will recognize the load and compensate for it.
 
uneek1976

uneek1976

G-Body Guru
Jul 24, 2009
603
41
28
Sugar Grove IL/ Chicago
#3
I thought that I read somewhere that I could use the wire off the low pressure sensor that does to the drier from the car but I'm not sure about that.
 
Ribbedroof

Ribbedroof

Comic Book Super Hero
Supporting Member
Jan 4, 2009
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2,165
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Wellston, OK
#4
That's the wire illustrated in the diagram, CCS is on the drier/accumulator.

The G body has a lt grn wire to it, and the dark green runs to the compressor. If you don't want to let the HVAC control head run the compressor, you will run the request wire from the drk green ccs terminal to the pcm, then add a wire to the compressor from the pcm A/C "on" output to the compressor clutch.

Seems like the long way around to me. Maybe the pcm cuts the compressor on WOT? That would be the only advantage I can see from all the extra wiring.
 
Last edited:
uneek1976

uneek1976

G-Body Guru
Jul 24, 2009
603
41
28
Sugar Grove IL/ Chicago
#5
The weird thing is that my connector for the switch on the drier has a black/white stripe wire and a solid black wire.
 
Ribbedroof

Ribbedroof

Comic Book Super Hero
Supporting Member
Jan 4, 2009
2,541
2,165
113
Wellston, OK
#6
Colors really mean nothing other than as a means to trace the circuit
 
uneek1976

uneek1976

G-Body Guru
Jul 24, 2009
603
41
28
Sugar Grove IL/ Chicago
#7
Ok with that being said, if I turn on the a/c from the dash would I be looking for a ground or 12v from that connector going to the drier so I will know which wire to use to go to the pcm?
 

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