I use my haltech to control the factory fan relays on my car, and I even use the factory wiring. Works way better than most of the controllers as I don't have to worry about the controllers frying themselves, (ask me how I know that one) and I have complete control as to what temp the fans turn on low speed or high speed.
gumby74 wrote:Cars equipped with a/c have a thermoswitch lined into the lower radiator hose.
The single slammers do, dual cam cars turn the fans on and off based on the the temp reading from the cts.