Radiator Fan Sensor
Thread Starter
Instructor
Joined: Oct 2007
Posts: 188
Likes: 3
Radiator Fan Sensor
I have a stock C4 1987. The radiator fan does not turn on and it overheats in traffic. The fan relay is new, and if I jump it from the relay connector the fan works. i think it is a sensor.
Where are the sensors? Also, is there a way to wire this to be on all the time the car is on? Last thing, anybody know the GM part number for the sensor?
Where are the sensors? Also, is there a way to wire this to be on all the time the car is on? Last thing, anybody know the GM part number for the sensor?
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
No sensor for main fan . is controlled by the ECM which gets it information from the coolant temp sensor (CTS ) at front of intake.
If this was faulty you would have other problems with engine.
Check the relay control wire back to computer.
Worst case you can wire the relay control wire to ground through a switch to turn fan on manually.
If this was faulty you would have other problems with engine.
Check the relay control wire back to computer.
Worst case you can wire the relay control wire to ground through a switch to turn fan on manually.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
There are two sensors in the front of the intake base just below the TB and slightly to the right of it. One is the coolant temp sensor the other is the control for the 9th injector.
If you open the small connector in the A/c pressure line just in front of the blower motor the main fan should run any time the engine is running. If not check the main fan relay, likely located just under the MC on the inner fender well.
If you open the small connector in the A/c pressure line just in front of the blower motor the main fan should run any time the engine is running. If not check the main fan relay, likely located just under the MC on the inner fender well.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Intermediate
Joined: Oct 2007
Posts: 40
Likes: 0
From: Abbottstown Pa.
I had the same problem with my 86. I replaced both sensors, one was inexpensive and the other one was around $70. The more expensive sensor was broken and glued back together (gifts from previous owner). I wired in a switch to manually turn on the fan while I tracked down the problem. After replacement I had to reset the error codes by disconnecting the battery for 10 minuets. Has been working well ever since.
