So I recently did the swap to 05+ fans in my 2000 Silverado. Got the harness from Lsx4u, it is a copy of the factory gm fan harness. Everything works as it should, I have high and low speed coming on at the designated temperatures, my only problem is that in this hot summer weather I need them to come on as soon as the AC is turned on, otherwise if I'm at a stop before the first temperature enable then the condenser can not get cooled off. I have done some reading on other forums and posts and have not been able to find a legitimate answer. Is there some tuning adjustments that would need done, or some sort of wiring change? Has anyone done this swap with success regarding the AC trigger? Thanks! BTW my tuner is using hptuners.

 

https://www.performancetrucks.net/fo...needed-539577/

 

You need to install the AC pressure sensor in the discharge line and use a 2002 OS, or connect your harness to the AC clutch engagement. Installing the pressure sensor is the "better" way.

 

Will the 2002 OS support the ac pressure sensor so it is actually operational? I know 01 back will not support it you can see it but it does not function. Now I'm curious If all I had to do was the 02 os to get the sensor to actually operate that'd be awesome.

 

Yes, Use and 2002 OS to enable the fans on a 99-02 truck

https://www.performancetrucks.net/fo...h-info-536648/

 

I'm in the same boat, what do I need to do to add the pressure sensor? can't find anything on that. Also I'm already running an 02 OS so that part is easy.

 

Need a compatible discharge line from the compressor to the condensor, the sensor itself, and the pigtail to connect to it and run wires to the PCM.

 

Question.. just did the swap on my 03 silverado followed the instructions per a instruction sheet from Retrofit electric fan kist lsxjustchevytrucks.com anyway they state to use green to pin 42 on C1 and the blue wire into pin 33 on C2. It stated if a wire was already in pin 33 on C2 to remove and place to side. However after doing that I have no a/c I believe that was a clutch trigger wire. thoughts? was tolds to tap into other wire. would like to avoid that

 

Wouldnt have the part numbers by any chance would you? Just want to make sure I'm buying the right parts lol

 

C2 (green) 43 is AC clutch relay control. The green wire on the fan harness goes to the blue connector and the blue wire goes to the green connector.