I am finishing up the wiring on my LS1/4L60E into a 1991Camaro and need some help & suggestions for wiring up the A/C. I’ve triedto chime in on some related posts but haven’t had much luck.

I am using a stand alone harness from TechRods whichincludes a single wire for the A/C RECOGNITION SIGNAL INPUT which accepts apower input signal for the A/C along with the original evaporator, condenser,etc. and the LS1 air compressor. The harness also has an extra relay wire in so that the fans come on when the A/C is turned on.

I’m really confused on how to wire up the A/C system as I’ve seen several different methods from using the PCM to control the A/C to utilizing a lot of the original 3rd gen system. From what Iunderstand it is mandatory to use the LS1 style 3-pin hi-pressure switch. According to Hawks, "You will use the stock 3rd Gen pressure switch on the dryer, but on the high side which is the small metal line you must use a 4th Gen pressure switch which is a 3 wire connector."

What all is reusedfrom the factory harness?

Which method of wiring the A/C should I use? Which one performs the best?

Thanks for any help!

 

What exactly does the harness have? Compressor clutch connector? 3 wire pressure sensor connector? Hi/low switch connector(s)?

AC request wire gets hooked to the HVAC harness (LT BLU)
Ignore the fan relay wire, the PCM will kick them on automatically

 

All I have that is not hooked to a sensor or connector on the harness I have is the for the A/C RECOGNITION SIGNAL INPUT. From what I can tell I will have to run new wires or modify the existing AC wiring to utilize the PCM setup right?

 

So you've got the AC request wire and nothing else. Odd to have one piece of the pie when it is useless without the rest. Well, wire it up like posted in the other thread using the 3 wire sensor and a relay

 

The radiator or coolant fan relay is already cut out of my original 3rd Gen harness, along with the coolant fan switch. There are now two loose wires that originally attached to these.

The A/C high pressure switch that originally went to the 3rd Gen compressor has been cut out as well since this is not on the LS1 compressor.

Whats the difference between the two methods in the drawings on this page (https://www.thirdgen.org/forums/ltx-...ng-i-need.html), PCM controlled and not PCM controlled? Is one better than the other?

 

Here's a picture of the original A/C connector. I think I'm starting to get a handle on this:

The light green/white wire (#1) goes to the control panel in the dash and out to R17 if using the PCM controlled unit?
The red wire (#2) runs to the starter and I assume gets reused no matter what method of wiring I use?
The light blue wire (#3) runs to the PCM as the A/C recognition signal (originally went to the A/C input at the 3rd Gen PCM)

The other black wire at the black connector in the picture is ground of course.

 

Did I get any of that correct?