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  1. #1

    Default First Time Post - Need AC Help 1999 2500 Silverado

    First time posting here so I hope I am on the right forum.

    I have a 1999 2500 Silverado (old square body style) with a 5.7 L . I had the AC charged and it was working when I press the AC switch and a light would come on. Now the light does not come on and I have no AC after maybe a week after it was charged. My ac/heater fuse is good.


    My questions:

    1. If my system is low on freon will the light still work on the switch?

    2. Should the light come on no matter what? How can I test this?

    3. Could it be my ac relay? What does this relay do?


    Thanks for an and all help.
    Tony-O

  2. #2

    Default

    Go back to same place that did your a/c and ask them to check pressure under warranty.
    If you DIY it, I bet charging port valve stuck open and leaked it all out.
    Why did you charge it to start with? If it were low on freon, system should have been tested for vacuum. If it was not done, now you have after effects.
    DON'T FIX IT IF IT AIN'T BROK. IF IT'S BROK - FIX RIGHT AWAY.
    WONNA THINGS DONE RIGHT, DO THEM YOURSELF

    2000 SILVERADO, CENTURION EDITION, 4WD, Z71, 5.3 VORTEC
    NO DUMM MODS

  3. #3
    Legend

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    Default

    you should return the vehicle because it sounds like they just put refrigerant into the system and did not leak check. also with a ac system like this the use of leak detecting dye is to be used and a leak check done. hopefully they used the dye when they charged the system.

    as was mentioned it could be a charge/test port valve is now leaking . this can occur when the vehicle is old the valves can fail to seat when disturbed.

  4. #4

    Default

    Depends on the controls you have. My climate control system's AC symbol will come on when I press the AC button/switch ... but if pressure is low it'll immediately turn back off. (I know because I've tested it while I had the system depressurized.) This implies there's something measuring the delta between the low side and high side pressure in the AC system.

    I can't speak to vehicles with manual controls, but it wouldn't shock me if the system won't come on if the delta between the low and high sides isn't above a certain measurable threshold (and there's a sensor measuring it, too).

    Stuck schrader valves are a COMMON problem. The low side schrader valve is usually serviceable. Unfortunately the high side schrader valve tends not to be -- meaning if the valve sticks open (which recently happened to me), you end up having to buy a new part (the one I bought cost 85 clams ... as it has the orifice tube -and- the low side port on it, too) and install it. It's mind-blowing that the high side valve is not serviceable like the low side is, specifically because the ball in the schrader valve sits in a single closed position for years, vibrating -- causing pitting, deformation, etc. The liklihood of it reseating in exactly the same position it was in prior to being used is low -- making the lilihood of it leaking after service ... high.

    So, pray it's not a stuck shrader valve ... or if it is that it's the low side, not the high side. Oddly, Fords and Dodges do it this way (non-serviceable schrader valves on one or more ports), too. I don't get it.

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