Ok, here's the situation...My 87 IROC overheats while sitting...only one of the fans(drivers side) comes on and it waits until the gauge is nearly pegged. I tested both fan motors and both work fine. I have replaced the thermostat with a new 160 unit and the car runs cool on the road. I was told that one of the fans should run while the A/C is on, is this true? mine don't. Could this be caused by a faulty fan switch(who put that thing in such a hard to reach spot )? or the fan relay? I'm putting new heads on this car this weekend and don't really want to cook them. Any help would be appreciated! Thanks!

 

Driver side fan (which has been working normally, correct?) is ECM controlled. The passenger side fan is controlled by a cooling fan switch. I'm pretty sure there have been pictures of it's location posted before. Look in the passenger side cyl head, between cylinders number 6 and 8. There is a switch there sticking out with a one wire connector plugged onto it. Pull the connector off and ground the wire. Make sure you have the key turned on. If the fan runs when you ground this wire, you have a bad fan switch and will have to replace it. If it does not run, your problem could be the relay, or the wiring.

edit:
Didn't realize you apparently have already found the fan switch. If you're swapping heads over the weekend though, it won't be any problem changing the switch while you're there....

 

If you want to solve all cooling problems, see my last post on the flex controller.