Electric Fan Woes

My (aux.)electric fan used to work.

Now it doesn't most of the time.

Sometimes it does, but more often than not, it doesn't.

It's supposed to turn on when the temp. gets to 210, but it doesn't except for some times, randomly.

The plug for it is tight and clean.

The fuse is fine, and I switched the relay with a known good one to no avail.

The plug is just a 2 connector plug, would that be one for power, one for ground?

Other than "jumping it" with aux power to see if it's a fan or electric issue, what else could I do to check?

Is there any reason I couldn't tap into the wires to send power to and jump the fan?

Thanks, this is a 92 XJ.

Yeah one side is power and the other is ground. Alot of people (myself inncluded) just wire the Aux fan up to a in cab switch. This way you can turn the fan on/off when you want for highway/trailrides/city traffic in the summer.

Chris

2000xjclassic said:

Yeah one side is power and the other is ground. Alot of people (myself inncluded) just wire the Aux fan up to a in cab switch. This way you can turn the fan on/off when you want for highway/trailrides/city traffic in the summer.

Chris

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For many, this isn't an option if you have a wife/daughter/female/somebody who doesn't pay attention that needs to drive it. It's also too easy to leave it on-thermostat has to open/close excessively.

I'm not familar with Chrysler ECMs, but likely the ECM triggers the fan via a relay based on what it gets from the Coolant Temperature sensor (it also uses this to adjust fuel mixture) You could, jump the relay and if the connection is okay the fan would come on. I have no idea where it's at on yours-but somebody else will probably chime in.

Next time its slightly past 210 (where the fan would normally be on), start moving around harnesses as this sounds like a poor connection somewhere. Obviously with the engine running.

Don't make a habit of letting it overheat-the heads will warp!

No no, it's not dangerously overheating, it's just over 210(maybe 215-220 at MOST).

For overriding it, where do I wire it in at?

FYI:The electric fan comes on at 220*...not 210*

What are you trying to override?Are you trying to have the fan operate like normal and have a switch wired in tandem so you have control over it?
Does your fan come on when you turn the a/c on?It should.....

outlander said:

FYI:The electric fan comes on at 220*...not 210*

What are you trying to override?Are you trying to have the fan operate like normal and have a switch wired in tandem so you have control over it?
Does your fan come on when you turn the a/c on?It should.....

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I'm pretty confident that it kicked on whenever it went over 210, but I could very well be wrong.

My a/c condenser has been removed, so I never turn on the A/C, but I'll try putting the switch there next time it warms up and see if that turns on.

If it's functioning normally and I'm just stupid, then I suppose there's no need for an override, but I'd rather have the fan on if it's over 210 at all, it just makes me uncomfortable.

Possible your gage is reading a little differently than it used to. There is a kit available so you can wire in a switch and an extra relay and have it work normally or when you manually turn it on.
My first guess is your gage is lieing to you, second guess is the temp. sensor in the thermostat housing is slowly failing.

You can test the sensor with an ohm meter, a thermometer and a pan of water.