Cooling Fan Issues
Thread Starter
8th Gear
Joined: Apr 2007
Posts: 8
Likes: 0
Cooling Fan Issues
I just purchased a 1994 corvette. My cooling fan will not come on. I've ran power to the fan and it works and the fuse is good. I know there is a relay but have no idea where it is. Anyone have any suggestions? Also have a problem with my cruise control. Again, fuse is good. Vacuum also seems good. I have no idea where to start. Any suggestions would be greatly appreciated.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
So your Vette overheats at idle or low speed? The cooling fan isn't suppose to come on until a certain temperature is reached - 217 or 219 is what I once read for the Main Fan for your Year - and then the Secondary should start spinning at 226. And though these numbers may be wrong, they're probably ballpark, so post what temperature your display is giving you. Signal is from the Coolant Temp Sensor, so use the Digital readout. Otherwise, if the a/c is running, the '94 should turn both fans on all most immediately, regardless of engine temp. Are they coming on when a/c is requested?
Thread Starter
8th Gear
Joined: Apr 2007
Posts: 8
Likes: 0
When the a/c is on the driver's side fan turns on only. I found the relays for the fans and swapped them to see if this corrected my problem but nothing changed. I guess what I'm saying is that I know my fan is good, the fuse is good and the relay is good. Where is the sensor that charges the relay?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
For '94, a/c fan signal is from the Pressure Sensor mounted on the high side. It's a thermistor with a 5 volt reference from the PCM. Return voltage increases with pressure. If I remember this right, 150 psi - about 1.5 volts from the Sensor, the PCM drives both fans (relays). Earlier Years (R12 instead of the R134 in your '94) used different pressures for each fan. If one fan is coming on, the Sensor is ok - Problem is in the PCM or wiring (since you've ruled out the Fan Motor and the Relay). I'd start with the wiring at the Relay. Whatever the number of wires, all should show voltage when driven by the PCM.
