AC compressor rattle

Discussion in 'Engine Performance + Maintenance' started by shorepatrol, Sep 19, 2020.

Car Parts
  1. gyver

    gyver Newbie

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    My compressor comes on when the a/c is turned off. Not sure if it’s supposed to or not.
     
  2. Kran

    Kran OBS Enthusiast

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    common issue when a transistor goes bad on the hvac control head/box. if the blower fan is off and the AC clutch is still engaged then stuff can freeze over. not good. switch the AC button off when you dont need AC. otherwise if you want to go through the hassle of adding a relay behind the dash to resolve that issue, look at this link. also has other useful info about HVAC controls https://www.silveradosierra.com/how...k-series-trucks-hvac-control-unit-t77522.html
     
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  3. df2x4

    df2x4 Domestics only.

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    Is the selector switch set to defrost? If so that's perfectly normal. The A/C compressor kicks on when the defrost vents are engaged to remove humidity from the air.
     
  4. S1I2F3

    S1I2F3 Newbie

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    Just throwing this out there...

    My AC was recently rebuilt, and was working great, blowing super cold air, with no excessive noise. As the engine would warm up with driving, there wouldn’t be any noticeable audible changes until I would come to stop light - once at idle the compressor was making this insanely loud clicking/knocking sound, to the point that I would turn it to “vent” when stopping since it was so annoying.

    Long story short, I got a new belt and that solved the problem (started with the cheapest fix). Logically speaking, as the engine bay would heat up, I suspect the belt would stretch slightly, and there would be enough slack for there to be an inappropriate amount of play in the compressor clutch, inducing the loud clicking. Since the belt tensioner cannot be adjusted, I figured a new tight belt might bring the clutch into spec.

    Might be worth a shot!
     
  5. gyver

    gyver Newbie

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    Thanks! You are right, it was!
     
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