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  1. #1

    Default a/c compressor not kicking on

    Hi all. I have an 05 suburban z71 w/ the 5.3 (non-flex). Last year it ran out of a/c so I took it in and had it recharged. They were supposed to use the UV dye. It again ran out of a/c so I got a refill kit with the uv light to see if I could find the leak...couldn't see anything. Either they didn't use uv dye or my leak is somewhere mysterious. Anyway, I went to charge it today with a UV charge, but now the compressor won't turn on. I put half a can in like the instructions said but still wouldn't. Are there any low pressure switches that turn the compressor off to protect it when it runs out of 134? How can I go about getting it kicked on to test? Hopefully the compressors do not have a history of going bad. Thanks!!

  2. #2

    Default

    Quote Originally Posted by jman308 View Post
    Are there any low pressure switches that turn the compressor off to protect it when it runs out of 134?
    Yep

    Quote Originally Posted by jman308 View Post
    Hopefully the compressors do not have a history of going bad.!
    Usually the clutch bearing goes bad, it will get real noisy. The compressor is mounted near the bottom of the engine, real close to the wheel and all the dirt and water kicked up by the wheel.

    You may have a line leak and, I suspect it is in the rear line(s).

    The 'burds have two evaporators (front and rear) and, therefore, require more R134 than a truck with only the front evaporator. The cans that I use come with a pressure gauge so you can tell when you have the correct amount, what are you using?
    Ray

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  3. #3

    Default

    Well, the compressor isn't even kicking on. I'm not sure which model I got, it had two cans and it did have a pressure gauge on it. I filled it up to the recommended psi for the ambient temp...should I put more in?

  4. #4

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    No, should be good.

    The low pressure switch is mounted on the accumulator, I think it is only two wires, pull the connector and jump the two wires with a paper clip.

    The accumulator is the thing that looks like an upside down aluminum can with a couple of pipes attached.

    Edit: just though, maybe you popped a fuse, they should be marked with HVAC

    Edit: answering an other thread just reminded me of the compressor clutch. To operate, the clutch needs the low pressure switch to operate the HVAC relay, which in turn operates the clutch relay. Both relays are mounted on the under-hood fuse panel.
    Last edited by RayVoy; 06-29-2013 at 06:43 PM.

  5. #5

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    jump these two? fuses look good. Can I swap the relays to test? Most of them seem to have the same number on them.

  6. #6

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    Quote Originally Posted by jman308 View Post
    jump these two?
    Yep

    Quote Originally Posted by jman308 View Post
    fuses look good..
    Can't always tell by looking, but it is a good start.

    Quote Originally Posted by jman308 View Post
    Can I swap the relays to test? Most of them seem to have the same number on them.
    If numbers are the same, you can swap.

  7. #7

    Default

    Jumped the sensor wire, swapped a/c relay (don't see hvac relay) and tested the fuses (hvac & a/c) with ohm meter....compressor still won't kick on. Can I bypass all the relays and jump the compressor straight? Anything else I should look at?

    - - - Updated - - -

    oh, not sure on the newer cars, but I remember learning that when you turn the a/c on, one of the fans is supposed to engage....neither fan starts when I turn the a/c on...

    - - - Updated - - -

    read on another post to jump the a/c relay from pin 85 to 30, I did so with the a/c running but the compressor still didn't kick on...thoughts?

  8. #8

    Default

    Quote Originally Posted by jman308 View Post
    oh, not sure on the newer cars, but I remember learning that when you turn the a/c on, one of the fans is supposed to engage....neither fan starts when I turn the a/c on...
    If your talking about the front and rear blower fans, I'd have to suggest there may be a blown fuse (or two).

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