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26/07/2021 3:38 pm
Topic starter
Hey Scotty, I have a 2013 silverado with 122000 miles. On a cold start when turning on my AC, there is a noticeable "thunk". However, AC and fan speed are not affected by it. What could it be? Thanks!
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26/07/2021 4:48 pm
It could be that your Serpentine Belt Tensioner is wearing out.
Inside there's a torsional spring and a damper.
The damper is plastic composite and it wears away over time. The spring also gets weaker over time. Additionally it pivots on an internal bushing which wears over time and causes "slop".
When you turn on the AC it adds load to the serpentine belt and a tensioner with worn internal parts would "thunk".
