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  1. #1

    Default A/C Compressor keeps turning itself on and off (99 Suburban) ***VIDEO INSIDE***

    Hello everyone,

    I just picked up a 99 GMC Suburban (K1500) and I am loving it. However, my air conditioning is not functioning and I am unable to find the issue. The previous owner had the A/C system serviced about two years ago and had a slew of things replaced in it so it was working at some point but it certainly isn't now.

    The issue (as seen in the video below), is that when the A/C is turned on, the compressor will activate and deactivate at a set interval leading me to believe there is an issue with the switch or something electrical. I already tried adding more refrigerant to the system but that didn't make a difference. I was searching around on this site (and others) and the only thing I found was that I possibly have a faulty pressure switch. What do you guys think?



    Anyway, this is my first Suburban and it's shaping up to be a really nice SUV for me. Can't wait to use it to tow my RX-7 to the track with it . Please help.
    Last edited by GetBoosted; 09-04-2010 at 09:01 PM.

  2. #2
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    murdog94's Avatar
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    Default

    Welcome aboard.. You most likely have a bad low pressure switch. Also you will want to actually check the low side pressue in the system to ensure that you do have enough pressue. It should be 40-45PSI depending on temp. Also If you want to figure out what switch is shot you can jumper(the connector side not the actual switch) the low pressue switch (as i mentioned your most likely culprit) and if the compressor stays running then you know that you have a bad low pressue switch.
    Let us know how it goes.
    Mike

    Currently

    1997 Chevy S-10 Blazer 4X4 with 330K miles and counting (Hunting rig).

    2009 Saturn Aura XE (wifes car)

    2011 F-150 Crew 4X4

    "Hold it to the floor till you see God.... Then Brake!!!!"

  3. #3

    Default

    No need to start my own thread. Got a 99 k1500 doing the exact same thing. With a pressure gauge hooked up to the low pressure side, I noticed when the compressor turns on the pressure is good but then immediately begins to drop. When it gets below 20 the compressor turns off. Pressure builds back to normal and it kicks back on again. I also notice that the "canister" on the pass side of the engine right by the fire wall makes a click when the pressure drops and then right before the compressor kicks back on it makes whats sounds like a reset click.

  4. #4
    Jr. Apprentice
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    both truck need to add more freon like maybe 1lb or so the pressure should be 35-45 psion the low side and the high side 200 - 300 about 250. been in A/C tech for over 15 years started when i was 15 in Florida. so A/C is a must in florida like 10 month out of 12.

  5. #5

    Default

    I BET ITS LOW ON FREON !!!!!!!!! fill and should be fine ...

    probably a slow leak, but normal for a over 10 year truck.....no worries

    1996 Suburban K3500 SLT DUALLY
    1988 Camaro RS 383 stroker LT1
    1992 32' Aero-tek Race Boat, 600 CI BBC
    WE CAN STICK A DIESEL IN ANYTHING
    SPECIALIZED IN CUSTOM CONVERSIONS OF ANY KIND
    Scott:glasses:

  6. #6

    Default

    Hi all new but i am an old MTech who now runs shops.First do not just ad freon 134A is not R12.You need to know to within a cple of ounces how much is in there it needs to be recover it.A great deal of the time a short cycling problem such as this is the result of low freon/or as someone posted earlier a bad low side pressure switch.I add freon 100 times more often than a bad switch

    But adding freon solves nothing gets some dye into the system have it filled ck for proper pressure and drive it until it starts short cycling again or the vent temp begins to warm.Then get to the shop that did the recovery and recharge and find out where the leak is so it can be repaired.Otherwise you just keep repeating it over and over.Freon does not evaporate and become absorbed by the system it is a closed system and if you are low you have a leak.period.

  7. #7
    Jr. Apprentice
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    for the cost of froen R134a is cheaper than having to buy a compressor or evap. i was a mtech for a/c too. for over 10 years. if you look on a R134A can it say FREON not R12. for one they dont make R12 anymore unless you can find someone that has it. but when you do work on a R12 unit its cheeper to convert over to R134A. even if its a bad switch you still haqve to add FREON to it.

  8. #8

    Default

    wow if the compressor is bad or the evap core is leaking just adding freon is not the way to fix it,but i guess we older guys were given a different set of ethics and quality of work matters to us.I cant even believe someone who does this for a living would say something as shade tree as the cost of freon is cheaper than a compressor..what happens when they put 3 13oz cans in a system that only holds 22oz.I know i fix that everyday...listen i didn't come on here to pee your leg,when you have some idea of what your talking about,then come talk to me.

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