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TOPIC: 1990 S4 AC not working

1990 S4 AC not working 31 Oct 2018 21:43 #20650

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This may be a simple question but I am trying to troubleshoot my AC system. I believe that when I push the AC button on the dash the AC starts to run, but I am not sure. What I do know is that button does not light up or stay in, but comes back to the original position and the Ac certainly does not work.

What does the operation of the button look like?
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1990 S4 AC not working 07 Nov 2018 10:58 #20656

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The AC button should "click" into place to stay turned on. If it doesn't, then the switch may be broken.

Try pushing in on the button and not releasing it. If the AC runs and cools, then you know the system is working. If when you release the button the cooling stops, that confirms that the AC system is working and the switch is your problem.

There may be something blocking the full travel of the switch to the bottom. Try slowly pushing the switch in and out with not too much pressure to see if any blockage can be cleared.
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