The cooling fan (radiator fan) runs all the time while the ignition is in the on position. I've replaced the cooling fan relay on the drivers side engine compartment. What could i troubleshoot to stop this fan? It does keep the engine cooler but it will lead to premature fan failure. Any help would be appreciated.

THanks, Burt

 

Its most likely the AC fan switch... If you look at the back of the compressor, you will see a wire at about 11 oclock and coming out at an angle. Thats the fan wire. The switch is about 40 bucks. You do NOT have to purge the system to change this switch. You will need a special pair of pliers you can buy at any auto store for a few bucks to get the hold down clip out. Then the switch just pulls out. Make sure you do not get any dirt inside the hole, and make sure you oil the new switch and O-ring with the proper oil.

 

As JonM suggested, it could be the AC switch. Before you buy one, just unplug it and see if it cures your problem. If the fan is still running, unplug the temp sensor that controls the fan. It's the one on the right cylinder head just in front of the #8 spark plug. Still will kill the fan unless you have a shorted wire going to the relay. If the fan stops when you unplug the temp sensor, then your temp sensor is bad. This sensor only controls the fan, not your temp gauge, so your gauge will work even if this sensor is bad. If you have to replace, go with the hypertech low temp sensor switch. It does cost a little more, but a cooler engine is more hp.

Dave

 

The high pressure cooling fan switch on the back of the A/C compressor is the most likely cause if you have rulled out the wiring going to the coolant temp switch isn't shorting out on an exhaust manifold or something. But I would advise you evacuate the system before you remove the switch. That is what is stated in the shop manual and it is what I have always done the switch has to sence high freon pressure and there may be some check valve in there of somekind( I have never checked) but still with R12 at $45.00 a can or lb. would you take a chance. I have never tried to change one with freon in it so I can not say it can not be done, all I do know for sure is that R12 is expensive, the shop manual says to remove the freon in order to change the switch and last but not least with the age of the car if there was some kind of check valve there is a very good chance it may not keep freon from leaking when the switch is removed I even fine this to be the cane when changing some on the line cycle switches which have schreader, they sometimes will not stop leaking when the switch is removed fro replace ment but it is not as big of a problem because it takes no time at all to screw the new switch on, but that would not be the case with the high pressure switch on the comprossor housing, just something to think about.

David Fulcher

 

Thanks Guys -
That sure helps. I'll check it out first of the week. Good to hear from you David. Hope things are well at Jumper. Let me know when there's a work day.

Burt

 

I have to replace my switch. Should the enginge be warm?
How is the wiring harness connected?
Thanks Chuck

 

Engine should be stone cold ; if you are fast enough you will only lose a little coolant.

 

 

22 dollars for harness and switch ac brand off amazon...on its way....

 

Wear gloves. Man, this thread is old.

 

My 84 went crazy after I overheated...Forgot to turn on the ac in city driving so fan would turn on...so hope this is a cure. Cost a 60 dollar tow when after she overheated, would't run...stalled...surged....fast idle...

I'll let you know next week...

 

Now life is back to normal
Fan on at 228 degrees
Thanks
Pigtail was toast...26 years not bad..

 

I have the opposite problem as of today. My fan doesn't come on at all, ac on or not. I will start at the fan assy and see if I have power, then the switch and relay. Probably wait till the weekend though. Guess I'll be driving the TBird the next few days.

 

Power to fan..ground..bad fan motor..bad switches..relay
Let the fun begin....

 

I have the same problem on my 85, fan runs all the time, but looks like the previous owner has straight wired the fan as the wires go in drivers side firewall. Dont know why anyone would have done this and dont really know what to do about it. Maybe he had trouble with relay.

 

Well, I got mine fixed. It was the thermo switch for the fan. I disconnected it and grounded it; fan kicked right on. The one for my 84 is discontinued by GM. Had to use a Borg Warner. At least I could get a name brand.