Electric Fan Questions..

IslanderOffRoad · Sep 17, 2006

I've viewed quite a few topics on the typical reasons the electric fan fails, and I'm at a point where I need to ask.

94 Cherokee Sport, 4.0 4x4 5spd.

Electric fan and A/C both do not work. E-fan won't come on when the a/c is turned on or when the Jeep heats up.

Attempted to recharge the A/C myself, bought freeze 12, followed the directions, nothing would go into the compressor.

Replaced the relays for both.

The next thing I'd like to do is test the motor on the e-fan as has been suggested here by hooking it up to a 12v. What I'm a bit lost on since I don't want to damage the fan is which wire on the fan is positive and which is negative. They're not black and red, and my chilton's doesnt tell me which is which.

Thanks for the help!

MogifiedXJ · Sep 17, 2006

It doesn't matter which way you hook it up. If you hook it up backwards all it will do is reverse the polarity and the fan will push instead of pull.

IslanderOffRoad · Sep 17, 2006

good to know

thanks!

Rocketman · Sep 17, 2006

MogifiedXJ said:
It doesn't matter which way you hook it up. If you hook it up backwards all it will do is reverse the polarity and the fan will push instead of pull.

You're saying that doesn't matter? It matters one hell of a lot. You want your fan to PULL.

Saudade · Sep 17, 2006

Funny thing is the '93 FSM calls out Black and Red wires on the fan in the text part but show Lt Grn and Black in the diagram.

5-90 · Sep 17, 2006

Rocketman said:
You're saying that doesn't matter? It matters one hell of a lot. You want your fan to PULL.

It doesn't matter for the sake of the test. A DC electric motor will run in either direction (according to polarity,) but if all you're doing is testing it, you can just hook it up. If it spins the wrong way, you can reverse the leads for testing, and you'll know which goes where when you're done (and can mark them, if you like.)

Since the test is typically done sitting still without the engine running, the direction the fan runs for the test doesn't matter. In normal operation, however, it damn sure does...

5-90

IslanderOffRoad · Sep 17, 2006

Ok, tested it.... the fan works.

If I'm understanding this correctly from what I've read here, the fan will not come on at all if the A/C does not work... regardless of whether it reaches 220* or not? Or should it still be comming on?

Fuses good, relay good, motor works... whats the next step?

How hard would it be to wire it so I can turn it on when I want it on?

langer1 · Sep 17, 2006

If you can't get the Freeze 12 in it's because you don't have the valve open on the compressor.

langer1 · Sep 17, 2006

If I'm understanding this correctly from what I've read here, the fan will not come on at all if the A/C does not work... regardless of whether it reaches 220* or not?

Thats not true, high temp will still fun the fan.

5-90 · Sep 17, 2006

The fan should come on when the A/C is selected OR the engine temperature trips the signal in the ECU.

It wouldn't be difficult - locate the relay, add a third signal to trip it (via a toggle switch in a convenient location) and there you go. I do it on RENIX all the time - I'd have to look up how to make it happen on the 1994 (on RENIX, I just wire a toggle in parallel with the thermal fan switch in the radiator. Fan on when A/C on OR at 220+ OR when the toggle switch is on.)

5-90

IslanderOffRoad · Sep 18, 2006

langer1 said:
If you can't get the Freeze 12 in it's because you don't have the valve open on the compressor.

How do I know if I have the valve open?

MogifiedXJ · Sep 18, 2006

Rocketman said:
You're saying that doesn't matter? It matters one hell of a lot. You want your fan to PULL.

You should really read. He's just wanting to test his fan...not hook it up. He was concerned about hooking it up wrong and messing it up...I informed him that if he hooked it up backwards all it would do is reverse the polarity and the fan would push instead of pulling...So no it doesn't matter which way you hook it up to see if it works or not.

langer1 · Sep 18, 2006

Take the big cap off the valve, under it is a valve stem, you need to turn in 2 turns, no more, that opens the port where the charge valve is.
Don't screw it in all the way, when your done screw it back out all the way and replace the cap.

Remove this cap.

From this valve

rick96xj · Sep 18, 2006

i put a toggle sw and a double pole double throw relay in line that way i can cycle the fan on and of when i'm offroadin works great had it that way for 5 years now

IslanderOffRoad · Sep 18, 2006

Thanks for the info everyone.

I picked up a 3 core rad this evening from another board member this afternoon, mentioned my fan problem, and he stated that if I unplugged the temp sensor on the t-stat housing the fan should turn on.

I did, and it turned on... so it seems like its comming on too late... at 220 it doesn't come on. Any ideas?

I may wire it up for turning on when I want it anyways.

Electric Fan Questions..

IslanderOffRoad

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MogifiedXJ

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IslanderOffRoad

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Rocketman

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Saudade

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5-90

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IslanderOffRoad

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langer1

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langer1

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5-90

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IslanderOffRoad

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MogifiedXJ

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langer1

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rick96xj

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IslanderOffRoad

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