AC stops blowing...

hjkjackshjkjacks Member Posts: 1
edited June 2018 in GMC
I've seen many similar posts on this issue. Here are my circumstances, none of which the dealer is able to recreate so it's become an unwelcome guessing game: we're on a 2+ hour trip in 90 degree weather on the highway. AC working great. Then the air stops blowing. Working the AC controls on the dash has no effect. But if we pull off and wait for 30 minutes or so, the AC will usually start again and work normally. Never happens on short trips, just the longer ones. The dealer is saying scan codes show nothing. They think it may be the blower motor ($285) and/or the Module ($240).
Thoughts or solutions found from anyone out there ???


  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 26,439
    Some other GMs had problems with blower motor not starting because of worn contacts on commutator and bumping it from below with the toe of your shoe would vibrate it and start it working again. But this one quits while running...

    I'd check the contacts where the blower leads plug into the power feed from the module for corrosion or signs of heat damage on the plastic of the connector. A poor connection gives off more heat and that softens and warps the plastic around the pin, letting the pin not make good contact. The heat expands the connectors. Sitting for a while lets them cool, contract, and make a little better contact again. The pin also will show burning from the poor connection.

    I mention this because it was a problem on some H-bodies years earlier. But while you're driving in high heat you're running the blower on a high speed while means more current and more heating on contacts. Conversely, if it's a milder day and you're running the AC on the lower speeds, does this happen?

    I have no way of checking the module other than buying a Tech II that plugs into the assembly line data link connector and watching the blower motor and module while driving. That's the plug in portable unit the dealers use.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • marvinkm1marvinkm1 Member Posts: 5
    hi hjkjacks; Try hosing off the radiator fins, if there is debris in there that could be it. Also, when the AC stops working try hosing off the condenser to cool it off. If the AC starts up again then the condenser needs work.Hope this helps.
  • thecardoc3thecardoc3 Member Posts: 5,535
    Things like this are easy to analyze when it doesn't work, the trick is to be ready to test when that happens. Access is always an issue so sometimes we may add a "tag wire" so that any testing can be done quicker. This drawing outlines how your Acadia needs to be tested.

    The green arrows are showing which wires have power to the blower controller and the blower motor. The Gray/Blk at the bottom is the command to the blower controller that comes from the HVAC control head. The only circuits that I didn't identify for you are the ground circuits. Now if you practice testing for powers and grounds when it works correctly and then are ready to test when it acts up you will go straight at the answer without guessing any parts.

    Here is what you should see.
    Red/Blk, battery power.
    PPL, could be battery power, but might vary with blower speed command changes. (The higher the speed selcted, the higher the voltage that should be measured.
    Gray/Blk. Varying voltage depending on the speed commanded.
    The black wire between the blower and the blower controller, could be 0v, might vary depending on the blower speed commanded.
    Black wire to ground from the controller, should be close to 0v.

    Again, make these measurements and document what you see when it works, then when it stops, measure again and see what is different.
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