Need help with with one. The AC harness passes through the firewall almost in the middle but closer to the passenger side head and then connects to the wiring harness close by the blower motor, ac drier, resistors, etc.. for 1991 year should this be a 4 wire or 3 wires on the male side. The female side I am seeing 4 wires in used harnesses. I can only trace 3 of them in the 1991 service manual.

 

And just to be a little more clear... the harness in the picture is supposed to be a 1991 Camaro TPI Engine Harness. Here as you can see there is only 3 wires, LT. BLU, RED, BLK.

On the other side of this connector coming from the AC Control head is the other side of C105, the female side. In all the pictures I have seen of this harness that connector has 4 Wires, LT. BLU, RED, GRN, BLK.

So my confusion is am I missing something on the engine harness side?

I cannot find a wiring diagram of the connectors that plug into the back of the AC/Heater Control Head.

 

The 1991 - 1992 TPI Engines (Non-Heavy-Duty Cooling Fan) do not use the Dark Green/ Dark Green with White Tracer Wire for the C105 Connector.

However the 1991 - 1992 TBI Engines do.

These TPI Engines will activate the Cooling Fan Relay via the PCM using corresponding Sensors.

These TBI Engines will activate the Cooling Fan Relay directly using corresponding Switches (No PCM involvement).




The Dark Green/ Dark Green with White Tracer Wire for the C105 Connector goes from the AC Control Head to the Cooling Fan Relay.
Shown below:

 

Thank you for the reply, so technically I could use the same AC Harness from my 89 with the 91 engine harness but cannot because of the different locations the C105 male connector is on the engine harness, 89 year it comes out of the harness just behind the passenger head area where as in 91 year it comes out of the harness close to the blower motor. I could create a jumper between the two or replace the 89 AC harness with a 91 and move on and not worry that there is basically a GRN wire not used in the 91 AC harness side.

 

So I’m in the same boat on this.
im horrible at reading diagrams. I’m still learning.
not sure what a white tracer wire is.
but I have a TPI engine harness and I’m not sure what year ac/heater harness.
my main goal is identify each wire. I’m trying to hook my ac properly with a sanden compressor.

c105

C105 with jumper wires? Do one of those go to the compressor for cycling? This is my main objective. Getting the compressor to the cycling switch.

C105 with red. Female side.(ac/heater harness) what wires are needed?

Ac/heater harness

 

How does my compressor tie into everything?
does it need to run though a relay for signal for clutch cycling?