Whining air-con

[SSBB]

My air con is making a strange groaning noise (intermittently), I thought it might be the bearings in the blower motor as when I switch the motor off the noise stops, however, if I switch the EC mode on with the blower motor still running the noise stops so I dont think it can be the blower motor bearings. Is there another motor behind the dash that Im unaware of? Or could the system just need a service?
The car is a C250TD 1999, 90,000 miles. The aircon works fine but is a bit temperamental as to when it blows hot or cold air.

 

[television]

My air con is making a strange groaning noise (intermittently), I thought it might be the bearings in the blower motor as when I switch the motor off the noise stops, however, if I switch the EC mode on with the blower motor still running the noise stops so I dont think it can be the blower motor bearings. Is there another motor behind the dash that Im unaware of? Or could the system just need a service?
The car is a C250TD 1999, 90,000 miles. The aircon works fine but is a bit temperamental as to when it blows hot or cold air.

Could it be the duo valve getting tight, that would account for temperamental bit

 

[SSBB]

I hadn't even considered that. Thanks, I'll strip and clean it and see what happens.

 

[MFK]

There is an excellent post in the HOWTO section on cleaning the duo valve.

However my air con was noisy in the exact same way as you described. It was due to a small leak from one of the air con pipes. Just check around them for dampness. On my E200 the ones that give trouble are the one behind the front LHS headlight - very accessible, the other one is visible through the small blank piece beside the fog lamp on the front LHS. Pull it out with samll screwdriver and you can see the pipe (use a torch). This is the most common one to fail. If system loses gas they get noisy.

Solution: Replace pipe, re-gas and all OK. Noise gone and car much cooler than previously.

Best of luck

MFK

 

[Wezzel]

For about a year my car had a noise like the compressor bearings were shot. Whenever I turned on the aircon there was a wirring/humming noise.

When I had the gas checked and topped up it went away and is now silent. It seems that it was caused by low gas levels.

Something worth checking