97 JEEP CHEROKEE SPORT A/C CLUTCH RUNS CONSTANTLY

Does the clutch run with the relay out? With the clutch wire disconnected? If so, the clutch might be frozen.

Also possible the relay is bad. swap with fog light relay and test.

Is the AC/heat selector in the defrost position?

Thank you for taking the time to help. I was there and I saw my mechanic take the relay out and the clutch kept right on going like nothing had happened. Then when he disconnected the wire it stopped becuse it had no power and he used a pen tester and there was power coming from the wire itself evethough the relay was still out of the housing. I will try your remedy and will respond again by the morning. Do you think the other problems could be associated to this as well?? Thanks again.

Thank you for helping. Actually it is not. The clutch runs from the time the key is turned till I turn the car off. Non stop. Even if I wanted just the fan to work it still cranks and cranks. If I try to turn the heat on for the little while it works I get hot AC. It's the weirdest thing I have ever seen.

Follow the wire from the compressor back and see if the insulation has failed.

I had to replace the computer in my large car because the wires had touched.

5 volt inputs don't like 12 volt sources!!

All, I can't see the wire this late at night but I will check it in the morning. I did try doing what DougW suggested regarding switching the relay from the fog light to the AC and the same result. I did make one huge mistake in the description of my problem. The clutch is not what is contantly running it is the evaporator. It starts to form a white film as soon as the car is turned on and freezes within just minutes. The clutch only runs when the car is on. When I turn the fan on the it kicks out cold AC. It only understands AC. If I try to turn it to 4 (high speed) then it start to hum and no air comes out at all. The same thing happens when I am entering the highway and have to accelerate quickly. The air flow cuts totally out and the loud hum start again. It's like inhaling really fast. That's the sound it makes. Then if I slow down 10-15 miles an hour it will kick back on but as soon as I speed up again it does the same thing again. I did take a look under the glove compartment and there are three more large black relays which I do not know what they are for but I am willing to bet that one of those suckers is causing me all this trouble. Do you or does anyone know what each of those three relays do? I gamble once in a while and I would bet the house that the problem lives there. Please reply when you can and have a great night.

This is for a 1993 ZJ. Your model might be different but without a schematic I can only guess.

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Power to the AC clutch flows like this.

Battery--fuse--->LowLimit Switch-->HighLimit Switch--->relay----->AC Clutch Positive The relay is similar to this one.

If the AC relay was pulled and the clutch was still working, then there is a short in the relay center.

Try disconnecting the high limit or low limit switches. Just disconnect the wire and that will cut all power to the relay (low limit is on the accumulator, high limit is on the back of the comressor) Ref:

If disconnecting the limit switch doesn't stop the clutch then your short is betwen pins 16 and either 18 or 19

If disconnecting the limit switch stops the clutch then the short is between pins 17 and 19

can only guess.

short in the relay center.

can only guess.

short in the relay center.

If they are like my ZJ, one is for door lock, one for unlock, and one for power antenna. There can be a fourth and it's for the alarm system.

No luck there either. I know there has to be a short somewhere. I just have to find this thing before it drives me nuts. Thank for all your help.

I don't know if this helps, but normally when the heater/air is affected by acceleration, you have a vacuum leak.

The dash switches are also known to melt down and fail.

Mike

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