Chevy & GMC Vans

This is a question to those who switched to all-electric rad-fans:

How did you guys setup switching of fan(s) regarding A/C operation?
Always on when A/C is on?
Or only when compressor is on?
Or when pressure (=temp) in the A/C-system reaches a certain point?
Or any other option?

Thanks
-Frank-

Before removing the factory AC system, mine was wired to come on when AC was turned on.

Although the best way is by using a relay triggered by the head pressure on the a/c compressor.

This ensures that the fans only run when needed. Over cooling the condensor can cause freeze up problems and shorten compressor life, plus it the fans draw a lot of power, etc.

The only bad thing is that I have no idea how it works or how to retro-fit this system. I'm sure Petey, the star HVAC man could explain it.

I read about it in the service manual for a 1994 LT1 Z28 that I used as a donor for my 1985 MC SS (still not finished ](*,) )

I have a nice variable speed setup. No high amp relays needed. It is setup to run at 50% regardless of temp when the AC is turned on. It then acts as normal after that.