Little Help with AC and Cooling Fan Control Strategy

[Lous69]

I did not study your proposed schematic. I just wanted to suggest that I believe it is possible to have your E67 control the fans as a function of both the AC pressure and / or the engine coolant temp.

Mikels, a member on this site, is going to reprogram my E67 to do that. He REALLY knows his stuff and he is very good to work with. He has never made me feel stupid no matter how basic my questions have been.

To let your E67 control the fans instead of the VA trinary switch I believe you will need to install a GM AC pressure switch and connect it to your E67. Then you will need to change the AC pressure settings in your E67 cal to compensate for the differences between the GM and VA AC systems.

You would still want to retain and use your VA trinary switch to protect your compressor but the E67 would control your fan(s).

If you want pulse width modulation of the fans (so they only run the speed needed to do the job) you will need to reprogram the E67 from discreet to PWM fan control mode and install a PWM fan controller like the one used in C6 Corvettes.

There is another thread in the engine section that talks more about the PWM control mode option:
https://lateral-g.net/forums/showthread.php4?t=40215