300E aux fan won't shut off
 

It runs constantly. This morning at first startup and each time I've checked thereafter.
I was reading a year old thread by csnow about the fan not coming on. If all the troubleshooting procedures are pretty much the same, it looks like it is over my head.

Should I disconnect the fuse to keep it from burning out? Or not worry about it until it gets to the shop in a few weeks?

Have you checked the engine temperature sensor ? If the aux. fan stopped when disconnecting the sensor it's likely the cause.

Yes, start at sensor.
Looks like this:

http://img.eautopartscatalog.com/liv...4512325BEH.JPG

Thanks guys, will do.

Should I disconnect the fuse for my 4 hr drive over the holiday weekend? I would put it back in if there was traffic, but that would be unlikely.
Don't want to burn the sucker out.

I disconnected the sensor with no change in fan activity, still runs.

Could you point me in the right direction? Thanks.


edit> originally by sjsfiji


I think this is what I'm looking for. . .

When you unplug the sensor, the fans ARE supposed to run.

Clear this with someone else first... but I believe if you jump the 2 wire connector you just unplugged, the fans SHOULD shut off. If they do, then your problem is most likely the temp sensor mentioned above. If not, you'll need to follow other parts of the system.

The temp sensor is cheap, so if it's old, the cost is small to replace it.

I think that rules out the temp sensor itself being stuck on, since you have to jump the sensor (zero resistance) to force the fan to come on high. At least on my model.

Actually, the fan will come on when you unplug the sensor.... so, unless we are saying the same thing, the sensor is still in play.

Of course, I have a '94 and your vehicle is basically the same as his.

Fan on 86/87 models does not use a thermistor sensor.
It uses the 3 prong , switched to ground system sensor.
You have a bad sensor or a stuck relay contactor.
Unplugging the sensor or relay will stop the fan..unless you have a bad ground in the harness.

sensor...
 

If you unplugged the engine temp sensor and it's still running, it must be running LOW. The problem would be your refrig. pressure switch at the A/C drier. Try unplugging that and the fan should stop. If it doesn't, you have a bad relay. I'm thinking that the HIGH fan aux circuit might be OK if the aux fan runs on LOW.

It was the A/C pressure switch. It was running on low and stopped after disconnecting it.

The A/C aint working right now anyway. . .

Thanks!