So I've read through tons of information regarding A/C wiring but most I've found regards using the 4th gen A/C compressor. Which I'm not using... I ordered a bracket from ICT Billet that allows me to use my 89 R4 compressor with the 98-02 LS1 accessory drive. So I'm hoping to keep this as simple as possible. Now... I'm using a Painless wiring harness which doesn't have any A/C wiring whatsoever. Having said that, the only wire that I need to hook to the LS1 computer is the A/C request signal wire correct? Which tells the computer to kick up the idle and turn the secondary fan on. If so then I'm going to pin it and run it to the compressor.

On the actual A/C wiring, I kept all of the wiring from the HVAC module that runs through the firewall with the Vacuum hoses for the vents. Up to the black four prong plug anyway. So I don't have the actual compressor, low or high pressure switch wiring. Would it be best to find a donor car to rip this out of or is it simple to wire up? As far as I know the A/C on these cars is actually controlled by the HVAC module and not the computer correct? My blower motor works and still has its relay hooked up as well as the heater resistor. Other than that though, all my other wiring is removed.

Hoping someone who knows more than me can shoot me in the right direction. It's only been 81 so far this Spring but my t-tops and leather seats make this car seem like a furnace inside. Ready to get my cold air going again!

 

The only difference between the 2 compressors is what connector you use.
Electrically it's exactly the same with either compressor:



Just get AC request to the PCM and it handles the rest. The pressure switch is on a million cars in the junk yard so go pick one up.

Add that wiring to the harness and you're set.

 

So I found my harness to the compressor, thankfully it was complete and intact. The only wiring I'm missing is the actual A/C relay. So it was originally located on the drivers side next to the brake booster correct? Guess I'll have to figure out how to wire this relay in, once that is done and the a/c request wire is ran to the PCM everything should work. Wish I paid more attention to this when I tore the car down three years ago.

I have the high pressure, low pressure switch and compressor connectors... all ran and plugged into the black plug coming from the HVAC connector near the firewall. So they should be good to go. I do have a question on that black three prong plug on the passenger side HVAC harness though... it has three wires in it, a black ground wire, a light blue wire which I'm assuming is the cycle switch wire, and a dark green wire. My plug from the compressor side only has the light blue and ground. I'll take a pic tomorrow to show exactly what I'm talking about. But I'm curious if that green wire is the A/C request signal wire that runs to the PCM?