Hello everyone,

I have been going through my donor harness, and trying to get everything figured out. The one thing that still confuses me is the A/C.

The harness I am working with is a 2002 Cad. Escalade. It's DBW, and I am hoping to retain that. I am swapping in a compressor from an LS1 Camaro, and I know that since the trucks of that time used mechanical fans, they don't have the 0-5v pressure that the cars do. I was reading that on the guide here: https://www.lsenginediy.com/upgradin...tioning-guide/ that it is recommended to start off with a Corvette tune, and I know that the DBW system on a Corvette is different. I would like to try and retain the current pedal and TAC module I have, because the Corvette's set up is very expensive. Am I able to add the A/C part of the Corvette tune and retain the truck pedal, or how does that work?

 

The truck ECMs can easily be programmed to add electric fan control.

https://www.performancetrucks.net/fo...ontrol-553385/
https://www.performancetrucks.net/fo...-chevy-484892/
https://www.performancetrucks.net/fo...h-info-536648/

The 2nd link is probably the most informative but they're all worth reading.

I HIGHLY recommend adding a dual electric fan to your car. I did that to my 04 Avalanche; MASSIVE improvement over the original clutch setup in every way. For the trucks it's beyond easy, because the fan assy just literally drops in, the bolt holes are even already there. Might take slightly more effort in a swap, but DEFINITELY worth every penny.

 

Great, this is good to know! Thank you for the reply.

As I am installing this engine in a 1986 IROC, I had heard that the AC doesn't go through the ECM (my engine was the LG4 carb).

So now I have to figure out how to wire up the compressor. The compressor is the car model and I am working with the truck electronics. I saw that the truck uses a Hi/Lo switch system, while the car uses a single sensor. Will I need to wire in a Hi/Lo switch, wire in a sensor like the 4th gen or do I just use the factory system and connect that to the compressor.

 

Seems to me the easiest thing to do would be to just use the car's existing AC control wiring and everything just exactly as it is (just change the pigtail at the compressor), wire the ECM's fan control wiring like the truck site shows using pins 33 & 42 of the ECM, and disable all the pressure switch stuff in your tune, since tuning is going to be required no matter what.

 

That sounds good to me! Thanks so much for the help on this. Then should probably just hook up the A/C control from my car to pin 17 to signal the ECM that my A/C is on. That should trigger the fan, and then I should be able to bump up the RPM to handle the load, etc.

As for fans, I got a 16" SPAL fan to replace the factory 16". I might go ahead and install a 12" or 16" pusher on the front, as well, and wire a relay for it and trigger it with A/C and a high temp that I will program in the ECM.