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Any AC or Electrical experts?

Discussion in 'Grand Cherokee' started by denraweb, Jun 11, 2023.

  1. Jun 11, 2023 at 11:20 AM

    denraweb [OP] New Member

    Jun 11, 2023
    So I got this WJ grand cherokee a few months ago and have been messing around with the AC a little here and there. Well today I dove deep into it checking everything that I can think of. But I still can't get the clutch to engage. So I've taken it to two separate places to have it checked. First place said they "thought" it was the AC transducer. So I replaced that, and still no dice. Second place was just a guy with an AC machine and some AC knowledge. He checked the refrigerant and verified the amount that was in it and said the clutch should engage. After looking over it for a few minutes, he concluded that there was an electrical issue somewhere. He was confident that his partner would be able to find the issue, but it would require me leaving my jeep at his house for a day or two. I got good vibes from the guy and he wouldn't even let me give him any kind of money for his time. But I'm still a little iffy on leaving my jeep with just a person and not a known shop. Any who, I'm hoping someone here can help me get the AC going as it's going to start hitting 100's soon.

    So my issue is that the clutch will not engage on the compressor. I replaced the transducer with an aftermarket, as well as tried two other Mopar transducers. No dice. Jumping the clutch relay (pins 87 & 30) turns on the AC clutch and the AC blows ice cold. Swapped out different working relays to no avail. The thing I noticed (and I'm no expert) is that the FSM shows relay pins 85 & 86 seem to activate 87a which looks like that it was triggers 30 to switch 87 on. But when I pull my relay and look in there, there is no contacts in the 87a hole. So it's basically doing nothing. I don't know if that is how it's supposed to be or if there is a contact that may have broke and that's why it's no longer making contact to trigger 30 to send power to 87. With the relay in place and everything on, there is no power going to the AC clutch. But there's still power going to the relay, but it doesn't click like it's supposed to.

    I pulled up the FSM and went to town checking continuity/voltage on anything I can find.

    Starting with the transducer: I checked pin 1 for ground, pin 2 for 5v, and pin 3 for continuity to pin 19 on the white PCM plug. All good.
    Moving on to the PCM, I checked for 12v at pin 1 on the PCM plug. I then checked continuity from pin 1 to pin 85 on the relay. Both good
    I then checked pins 86 and 30 on the relay for 12v. Both showing power.
    I then checked continuity from pin 87 to the A/C compressor
    Moving to he automatic zone control, I checked the AZC black plug pin 9 (A/C switch signal) for power. What I noticed here is that with the AC button "ON", I was getting 2.7v out of this pin. And with the AC off, I was getting 12v.

    The only thing I haven't checked yet is the body control module which the FSM shows that pin 9 on the AZC goes to the BCM.

    All fuses that I can find that had anything to do with the AC, relay, clutch, or BCM were checked and all found in working order.

    I know it's gonna end up being something small, but I'm just about to give up as the frustration is too much. If you have any suggestions, please let me know. Thanks!

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