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1999 Dodge Viper Question: The original ac compressor stopped pumping but the clutch still works.

 

Question

moparlou, Stillwater, OK, August 12, 2013, 19:57
 Rookie

I replaced the compressor with a new one and the fuse blew. It seems that the clutch coil was shorted. So I ordered a new compressor. I tested the clutch and it activated with 12 volts. I replaced the compressor again. When I plugged in the car connector, it blew another fuse. Now that clutch wont work. I hook up the old clutch and it works fine. There is an electrical difference between the new clutches and the old clutch. What is the difference. I am frustrated.

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  • Answer #1

    August 13, 2013, 02:29
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     Master

    It ain't the clutch coil, find short in circuit going to it! The difference is the position the wire(s) are in with comp. installed. Blow fuse after charging system or else how are you sending voltage to the comp.?

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    moparlou, August 13, 2013, 19:45
     Rookie

    I have 50 years automotive experience and I have never seen this happen. ac compressor repairs are fairly simple, UNTIL WE STARTED TO HAVE PARTS MADE IN CHINA (WHERE THIS APPEARS TO BE FROM). When I worked for B&D, we had A MILLION DRILL CALL BACK BECAUSE OF CHINESE "WORKMANSHIP".
    I hooked the old compressor to the wire harness. No fuse blow, old clutch works fine. This would indicate no short in the wire harness or the 12 volts going to the clutch circuit. The supplier is going to look at the first returned compressor to see why the clutch failed. They said they only have 1% failure rate for this. My immediate course is to take the old clutch (which works) and swap it for the bad clutch on the new second compressor. At this point, I am checking coil resistance. Supplier says that the coil should measure 3 to 5 ohms, and mine measures 4.4 ohms, hence why mine works. The FIRST clutch measured .08 which tells me a wire in the new unit was internally shorted. I clipped new leads to THE NEW UNIT and it measures .8 which is what the leads measure, so it is shorted. I am waiting for a few days for the supplier eval.
    It may be bad luck, but I think that out of the batch of 3 units that the supplier ordered, two were bad. He pulled the third unit and the coil measured 3.7 ohms, so it should be good. They say their units have a diode and even if the diode blew, it would register open, not short.
    The saga continues.

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  • Answer #2

    Greg's Orange Auto (14238 Answers) , Orange, CA - (714) 361-9386
    globalhelper August 13, 2013, 05:48
     Master

    agree with push rod

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    moparlou, August 16, 2013, 10:24
     Rookie

    OK,
    Here is the answer to the mystery. The clutch manufacturer used a diode between the 12 vdc wire and the neg wire AT THE CONNECTOR. These were chinese and were not able to take the power surge from the vipers electrical system and blew. When they blew, they shorted. This happened to two compressors. The supplier opened the shrink tubing on the connector wire and cut the diode out of the circuit. When they did this, the clutch worked fine. All I have to do is cut the shrink tubing, remove the diode and the clutch should work without removing the entire compressor. Since the diode is not visible, I assumed it was internal.
    Problem solved.

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    pushrod, August 16, 2013, 15:24
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     Master

    OK. Most of them have that diode!!! As long as it works when you remove the diode, then problem is solved!

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