Radiator Fan Not Working Correctly
 

Hi everyone,

I have a 1984 5 speed manual 928 which is finally running strong. My new problem is the coolant! light is on and the radiator fan is not working correctly. The fan will turn on some of the time at about 3/4 up the temperature gauge on the dash. The radiator fan was modified to electric driven and is spliced with the A/C fan. The A/C relay is in and working properly. Does my sensor at the bottom of the radiator need to be replaced? How can I check the sensor to see if it is working properly? And, what temperature should a 1984 928 run at when idling? Thanks for the help.

Spencer

Why did they connect the AC relay to the fan? These modifications present a whole new series of problems. I take it your belt driven fan was removed? It is one thing to trouble shoot a stock set up and another for one that has been modified. I guess you can jumper the sensor to see if it turns on the fan. Is the motor really over heating? My electric fans do cut in only at high temps.

The belt driven fan was removed from the car and was replaced with an electric fan that is spliced to the A/C fan. I am unsure as to why this modification was done. The previous owner supposedly never had a problem with the car staying cool. I can upload a picture of the set up later today. Should I try to find a belt driven set up and replace what is there now?

I would try and determine what was done and trace down the wiring. If you can find the instructions on what he did that would help. People here have replaced the belt fan and gone all electric. Hopefully someone here has done it and can provide you more help. You might do a search on installing the electric fans and see what comes up. It may show how it is hooked up. As with many electrical issues on the 928, it is usually related to fuses, CE panel, bad grounds, bad switches, relays and sensors, ground strap.

There is some relevant info "electric fan" thread dated from 5-8-13.
If PO wired cooling fan to only kick on when A/C fan is running then you will only have a fan on at high temps., which sounds like what is happening.
You may not have any failed components. But, I would trouble shoot first like Harborman said and then try and wire fan to register coolant temp., this can be done without a lot of work.

I think you have a great idea. The fans will only come on if the A/C is on it would seem. If it was wired that way. So if the belt fan was removed you have no cooling fans with A/C off. He should check that out.