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strange sound from AC.

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Old 05-24-2011, 08:45 PM
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C240
strange sound from AC.

Guys, whenever I turn my AC on and changed its temperature to around 22c or over, I can hear some boiling like sound from the right side of my engine (from driving position). And my steering is on the right side.

Problem never occurs below 22c, and if I turn the temperature down back to say 18c, the sound goes away immediately. I have changed my compressor some time ago, but I'm not sure if this problem is already there prior to compressor change. Any ideas?
Old 05-25-2011, 11:05 AM
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late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
I think it is when you start to get some hot water flow to control the temperature. Settings below 22 deg C require the cooling side of the system to run flat out to achieve set temperature. Above 22 C you need some warm air mixing with cold to achieve the set temperature which is achieved by diverting engine coolant via the HVAC unit's small radiator. Might be a little air in the cooling system or the secondary coolant pump or water noise at the coolant control valve.

Attached Thumbnails strange sound from AC.-heaterbox.jpg  
Old 05-25-2011, 11:06 AM
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Holey Crap, you wanted an answer and you sure as hell got one! Nice diagram. Explains it all. Thanks...

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