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  1. #1

    Default AC Running all the time, Even if on HEAT..

    When i run my heater on Hot for defrosting the windsheild my AC is running, i got out to check after a drive today and the Silver AC condensor was freezing cold, but i was running the heater? has anyone seen this before,
    if the heater is on in heat mode, should the AC kick in and get cold under the hood,

    Last edited by Tilldogg; 10-03-2012 at 10:26 AM. Reason: No replys

  2. #2


    Welcome to the G M T C ! I can't help, but if you post in one of the "Technical" forums on this site you should get some good information. Good luck!

    2010 Z/71 Colorado C/C
    Black 4X4 w/5.3L V8
    2007 Winnebago Adventurer
    w/8.1L Chevy & Allison 6spd.
    Canyon Lake, Texas

  3. #3


    Thanks , i will try that, a buddy says this is how it runs, the AC and heater will run together on defrost? i find that hard to belive, i will give it a shot,
    happy motoring

  4. #4


    Defrost activates the AC compressor. This happens for 2 reasons. First, air conditioning works by drying the air. If you have moisture on the windshield, the AC helps dry it up instead of just heating it up. Second, It runs the compressor to keep the oil circulated through the air conditioning system during the months that you wouldn't use the air. The worst thing you can do to an AC system is not run it. It causes seals to dry out and leak. This is perfectly normal operation and does not need to be "fixed".

    GM vehicles do this in defrost mode but some other vehicles do it in other modes too.
    "It went together didn't it? Well then there has to be a way to take it apart!" - Me.

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  5. #5


    Well that explains alot Moogvo, it sucks for the fuel economy haha, does this work well when its all frozen up, as the UK in a month or two will be Snow and Ice ,
    Not looking forward to that in a rear wheel drive haha,

    Good knowledge from you,

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