Electric fan won't come on....at all.

[gw204]

Guys, I'm looking for suggestions beyond the standard responses for why the electric fan won't work. Mine doesn't come on when the engine heats up or when I turn on the A/C. Granted the A/C itself doesn't work....

Anyway, I've replaced the fan relay and jumped the fan directly to the battery. The latter made it spin, so I know the fan itself is good.

What next....temp sensor in the thermostat housing?

Thanks.

[outlander]

On my 89 There is a temp sensor at the lower half of the radiator(air box side)that is another culprit.But newer models may not have it?

[gw204]

Sorry, I thought I had the model info in a sig. Guess not. It's a '91 and unless I missed something, there's no sensor in the radiator.

But I know what you're talking about. My '88 had one in that same location. :)

[Digger87xj]

year of the jeep would be good info... they used two different systems between renix or chrysler

if it is a 87-90 there is a switch in the radiator that turns on the relay at about 180* radiator OUTLET temp.
there is also an "electric fan diode" located in the harness just under the airbox. it is in a little orange connector and can be removed with a pick. you can get them at the dealer...it will take them a bit of searching to find it in the book.

91 and up... the PCM turns the fan relay on with a/c request and engine temperature data from the coolant sensor in the thermostat housing.

if it doesn't come on at all I'd check all fuses

[freewithfire]

I was in the same spot as you are, with AC that doesn't work, a fan that wouldn't come on, and a '91 XJ. I wanted the ability to use the aux. fan at will, so I just bought a fuse holder and a switch, and wired it up myself. Now I can flip the switch whenever I feel like using the fan, and kill it whenever I see fit. That's the way I'd go (and did go!). The whole project took about 30 minutes and cost about 12 bucks.

Andy

[treedoc]

second the vote for a manual switch. did it when all the the complicated stuff failed. went ahead and ran a switch for the a/c compressor(which i thought was dead too) on the same fuse. now they both work!!!

[Dr. Dyno]

Guys, I'm looking for suggestions beyond the standard responses for why the electric fan won't work. Mine doesn't come on when the engine heats up or when I turn on the A/C. Granted the A/C itself doesn't work....

Anyway, I've replaced the fan relay and jumped the fan directly to the battery. The latter made it spin, so I know the fan itself is good.

What next....temp sensor in the thermostat housing?

Thanks.

Yes. Check the resistance across the two pins of the sensor with a digital multimeter. If it reads infinity, the sensor is definitely bad. If it's OK, make sure the wiring to it isn't frayed or broken, and check the wiring harness connector to the sensor.