My 89 Formula 305TPI is overheating after 15-20mins. I'm talking maxing out eventually and not either of the fans are working. I've been told by alot of people that it is most likely the fan relay motor. How do I fix this? I dont want to rig a manual fan switch I want it just like the stock setup with the ecm like its suppose to. If I can get a list of instrucitons on how to test to make sure it is the switch and hwo tio fix it I will be very grateful. Thanks

 

Set it up for code retrieval using the ALDL connector. During that procedure the primary fan should run. You can substitute the blower motor relay for the fan relays for testing. When in doubt replace BOTH fan control relays.

 

if i was you i would make sure that the fans are not receiving voltage at time the car is getting hot and you can do this with a volt meter unplug the fan connectors and at about 230 i would connect my meter and see if the wiring harnesses are getting voltage. do not let the car go beyond 235 if single fan setup and 245 dual fan setup.if you do receive voltage then i would straight wire the fans to the battery and see if the fans kick on . if not bad ban fan motors i would then go to the relays after trying these steps if you dont know how to test them have them tested at auto zone if they are good then i would go to the fan temperature switch it is time consuming but it will save you money.good luck

 

My fans aren't working either, but the relays work when I ground them out. could it be the ECM as well? A friend had a problem with his ECM, swapped it out and the fans started to work.

Access to the fan switch in the head is pretty tough with the stock manifolds, A/C and smog.