I have an 89 Iroc with the duel fan setup. In the years past i rewired the fans back to stock after they were hardwired to switches with no relays. The car was an AC car but all of that has been removed. The issue i am having is getting both fans to kick on and stay on. One fan will kick on when the computer requests it but the other that turns on when the AC is on or the temp reaches 235 i believe the stock temp is. So what i did was hooked the AC switch wire that activates the fan when the AC is turned on to a grounded switch and it works great when the car isnt moving or at or above operating temp. Today i rewired the switch to turn both fans on through the wires that come from the ECU so that i basically bypass the computer and am able to turn the fans on as long as i want to what temp i want. It worked great went out for a test drive and the car stayed cool for the bit i was driving it. then it started to get hot the switch was on so in theory both fans should be on. when i parked it both fans were off no matter is the switch was on or off and i even looked at all the wires i just put in nothing. i turned it off for a few min looked at my wiring and still nothing. then i turned the ignition on to test again and they started working again. i am so stumped by this fan issue and im about ready to just hot wire these fans and be done. Anyone have any ideas what might be going on and how to fix it? Bad computer? short in wiring? thanks for any help

 

I had sort of the same issue with what I just put together. I had both of my fans Wired from the switch and one of them would stop working. I bought a set of dual fan relays from Jegs and put on them and now they both kick on at 195 and kick off at 165. No more issues with either fan not working. Seems like in my case the one fan motor was getting hot and it would shut the fan down, and your case perhaps both of them are getting too hot. I'm no expert on any of this, listen to the next guy. Just sharing my experience.

 

Not sure what could be going on but its most likely in the switch or the ground. Maybe ground location connection or something like that. Assumption being its just a basic SPST toggle switch, it nor the ground have any reset after cooling behavior. Both main power and coil voltages are fed by fuses so they wont act this way either. It is probably a simple intermittent connection issue. Check control voltages at the switch when it is acting up and follow it through your wiring connections.

 

i will have to check all connections for sure. the switch im using is a 20amp switch so it should have no problems with the switch wires.

 

how did you wire it up? did you cut wires or just but new connectors for the fans. i already have the new wiring for the fans from the main harness connector for the fans to each of the relays and to the fans.