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2 interior issues, unrelated but one post A/C and a Seat Belt

Discussion in 'Interior' started by Nicolai8775, Jul 24, 2020.

  1. Nicolai8775

    Nicolai8775 Member

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    I'm trying to get these sorted out before I road trip.

    First issue is the A/C. It works and blows cold say if it's Sunny and 75 out, but if it's a heat wave 85+ it just doesn't even engage the compressor. I know this because I used a test light and turned on the AC, didn't get 12V. But if I disconnect the green wire on the pcm for I think it was the low pressure switch or whatever tells the compressor to kick on, and use the test probe to push 12v through it the light will turn on. So that wire is capable of pushing 12v. Shop said that means the resistor is bad in the PCM. Well I have 2 similarly tuned computers from Black Bear and I swapped it out, and the A/C compressor still wouldn't turn on. Either I have 2 bad computers from my tuner or something else is going on.

    The second issue is the passenger seat belt. If someone sits in the seat the seat belt will not come out. It locks up. If they arch their lower back off the seat it no longer senses a passenger and will allow the belt to come out. Really annoying for passengers, especially with no A/C
     
  2. Doubeleive

    Doubeleive Supporting Member

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    on your passenger seat the only "sensor" would be a plastic sensor that turns the passenger airbag on or off and that is only on the 03+ I believe, it's probably something pressing into the seat belt mechanism, you will need to either replace it or take the seat apart and inspect for what the problem is.

    @UmmScott could probably assist you with the ac issue, have you checked the system to see if it is full? when the r34 get's low they can get picky about when they decide to work or not and if you have the digital control inside those can go bad also.
     
  3. Nicolai8775

    Nicolai8775 Member

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    Oh jeez I forgot the most important info, this is a 2001 Tahoe lol. We did make sure the system was charged. I don't know much about cooling but he said the pressure was really high, which would also cause the compressor not to work, so he evened it out for me and after it still didn't work we started testing the electricals.
     
  4. Nicolai8775

    Nicolai8775 Member

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    Now that I think about it, I've had this problem for years now, even BEFORE I had a tune from Black bear on the stock PCM, so something else is definitely going on that interrupts the 12v. As for the seat I'll take that out today I think. Any guesses on where to look? I guess I'll start in the lumbar area since that's where it seems to trip something
     
  5. UmmScott

    UmmScott Full Access Member

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    Ok so basically the 00 thru 05 models, the climate control head simply sends an AC request on the class 2 serial data comm to the PCM.
    PCM handles engaging/disengaging clutch.

    Best to have a scantool that can see that info. We gotta confirm that the PCM is getting an AC request. If its not then you'll dick and tinker with whatever you want under the hood and itll never come on on its own.
    Those climate control heads do weird things when they get old, especially the digital ones.

    Now...if we have confirmed that we're getting an AC request, the PCM looks at the low pressure switch. If its closed and the high pressure safety (located on the discharge line or compressor itself) is closed, then PCM should ground the green wire bringing on the clutch.
    If...at any time those switches open for whatever reason, the clutch will disengage immediately and wont reapply until the switches close plus 3 ADDITIONAL seconds.

    If this issue is erratic like you're saying, then id focus more on an electrical issue first.
    Ruling out the climate control head will really help you out here.

    Hope this helps. I have been so busy with ac work i haven't had time to think straight

    Sent from my SM-G975U using Tapatalk
     
    Fless, Nicolai8775 and Doubeleive like this.

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