Noisy Engine on CLK

I've got a 2007 CLK550 that emits a loud whining noise whenever I cold start with the A/C on. Once the engine warms up and the A/C slows up a bit the
whining decreases. I've asked the dealer about it but they just shrug it off & say it's normal. It's difficult to demonstrate as whenever I'm at the dealer the engine is warmed up and doesn't exhibit the excessive noise. I would appreciate any advice as to what's causing the noise.
Bstuttman
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Burton Stuttman ha scritto:

Maybe it's just the belt that's sliding. Checking correct tension and/or exchanging belt (check tensioner, too) might be the solution. Belt: I mean the belt that transmits engine rotation to the A/C compressor.
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I haven't seen that engine yet but I would have to say it is the idler pulley... the wheel that just spins. It is most likely attached to the tensioner or independent and regardless of which... the pulley itself is replaceble.
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