Grenkepr

I have an 88 that is over heating badly. Radiator fan won't come on at all, but the aux. fan will come on as it should at 238. Neither one of them comes on when I turn on the a/c. I have replaced the therm., all hoses, water pump, cleaned and flushed radiator, replaced the fan motor and its relay. I have not replaced the temp. sonsor in the block. Someone told me to disconnect the wire and ground the wire. If the fans did not come on the sensor was good. I did that and the fans did not come on. So I assume sensor is good. Any thoughts.?

AGENT 86

Test the ins and outs of relay. There is a fusible link between relay and battery, that may be blown.

Also, there is a fan fuse in main panel, that may be blown.

http://members.shaw.ca/corvette86/Co...%20Control.pdf

c4cruiser

The coolant temp sensor that is on the driver's side cylinder head controls the Aux fan only, not the main fan. You can test this sensor by turning the ignition on and grounding the green wire; the AUX fan should run. But is sounds like the AUX fan is working properly if it comes on when coolant temp reaches 238.

If you jump pins A and B on the ALDL and turn the ignition to the RUN position, does the main fan come on?? Check the fuse for the coolant fan Should be a 3A fuse in the top row and labeled something like "3a FAN".

The relay for the main fan is (or should be) near the brake booster and attached to the lower fender well panel Look for a number 10038311 on the cover.

Remove the harness from the fan relay and using a jumper with an in-line 20A fuse, connect the large red wire to the black wire (don't need the ignition on for this). Does the fan come on? If it does, the relay is bad.