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Thread: charging ac

  1. #1
    Jr. Apprentice
    Join Date
    Jan 2012
    san antonio tx

    Default charging ac

    im trying to charge my ac in my 88 GMC, its after market 134a,put in one 12oz can and clutch comes on and off no cool air put second can in have cool air but the clutch still goes on and off. low side is 30-40 high side is 100. outside temp is 80 with a fan blowing in the condensor. i don't want to over fill it do i have an obstruction?

  2. #2


    I don't know anything about ac systems. But where do you live that you're doing this now? Lol. Just an observation.

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  3. #3


    This chart seems to be representative of what I see for 134a AC systems I've used this table when working on my own AC system, too, so I think it is right. According to this, it looks like you are still low on refigerant.

    Have the stickers from the 134a retrofit survived? What do they say the max charge of 134a should be?
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  4. #4
    Jr. Engineer poncho62's Avatar
    Join Date
    Sep 2013
    Hanover, Ont, Canada


    My 97 holds 2 lbs of refrigerant. I imagine yours is similar. My AC guy says adding using those cans is not the way to do it. He says, all refrigerant should be evacuated from the system, weighed and then you know exactly how much to put back in.

    1997 GMC

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