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Billy, Trainer/ Master Technician
Category: Audi
Satisfied Customers: 3498
Experience:  Trainer 8+ years, master tech. 10+ years, SAE member
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My 2006 Audi A3, with about 96K miles, most of it in south

Customer Question

My 2006 Audi A3, with about 96K miles, most of it in south Florida, makes a chattering/squealing sound when starting from a dead stop, only when the A/C is on. I have replaced the belt tensioner, albeit with a non-OEM part, with no change. I think the A/C compressor (Denso/Valeo) is suspect, perhaps having some initial, high initial resistance. The A/C seems to be working normally. There are descriptions on the web of other auto brands encountering this problem, due to the low position of the compressor and locking up with refrigerant. Question is now whether the compressor should be replaced.
Submitted: 1 year ago.
Category: Audi
Expert:  Billy replied 1 year ago.
Hello and Welcome! I'm Billy and i will assist you with your inquiry. Feel free to ask if any further info is needed.
You only replaced the belt tensioner? the belt was not replaced?
the squeal and chattering noise appear when the A/C is turned on? or when engine is turned on?
did you check the compressor pulley for noises (using a stethoscope)?
Customer: replied 1 year ago.
The ribbed belt was just replaced at a dealership, when the timing belt was replaced. Noise only occurs when the A/C is on & car is starting from a dead stop (or nearly so). No noise when the engine is running, A/C is off.
It was looked at by an independent repair shop-they said the (new) tensioner was the problem, after applying some additional tension to the belt using a wrench. They did not check the pulley for noises. Old tensioner was replaced 2 years ago.
Thank you
Expert:  Billy replied 1 year ago.
I would double check the pulley for noises, to confirm whether it's coming from the tensioner, or the compressor. They way to do that would be using a stethoscope while the engine is running and engine is on.
You can also remove the drive belt, and turn the pulleys one by one (however this time with engine off), to confirm the noisy culprit and replace accordingly.
As even if the noise is from the compressor pulley, this might be repairable (replacing the pulley and clutch and bearing on the compressor unit).
Get back to me with your findings, or if further assistance is needed, so we proceed accordingly.

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