I recently installed a Derale adjustable fan relay to an otherwise stock '87 dual fan setup. The relay has a radiator temperature probe to determine the on/off threshold. The problem I'm having is the fans do not turn on without the A/C being on (even with the adjustment turned to the lowest setting on the relay). Is this occuring because of the stock ECM settings? Bad RElay?The wiring to the fans just replaced the "+" leads with the adj. relay leads. The stock "-" leads are still connected. Any suggestions or experience will be appriciated!

 

Use the adjustable stat to ground the relays, just as the old temp sensor did.

Another "dirty" method may be to actually create a circuit using the ac switch (high pressure switch). Grounding the relay.

Unless of course the stock wiring is screwed up...