Hello to all from a new user!
My '84 380SL has begun making a humming noise that increases with engine speed when the compressor is on. The air still blows cold.
I have been told that the Expansion Valve is bad, but wanted another opinion before taking it for repair. I assume, from the year of my MB, that it uses R12 refrigerant?
Thanks for any help and advice!
John Daly

I am replying just to let you know we are not being rude to a new poster. It's just difficult or impossible to diagnose noises with nothing but written text. If we can't hear it for ourselves, it's difficult to know.

If it were the expansion valve the noise should be coming from the expansion valve. If the noise is coming from the compressor, it's the compressor. Just because it's noisy does not mean it needs to be replaced.

Hope this helps,

The compressor does make a slight humming noise uder normal operation, as stated before, it is difficult to tell if it is normal or not. If everything is working fine, I would not be too quick to throw parts at the car.

You are correct, it uses r-12, unless it has been converted.

__________________
Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

Thanks for the input, Larry & Ali!
My climate control is still making noise and seems to be getting worse. It does still blow cold air, but I'm afraid of making the situation worse by using it. A vibration can actually be felt, especially through the accelerator. I have checked for TSBs on AlldataDIY, and there is one listed (Job #83-510 and 512) about noise coming from the compressor and it states to check the function of the Expansion Valve.
Unfortunately, I know very little about air conditioning/climate control systems, however, I live only about 40 miles from Gainesville, Florida. As such, I believe I will take my car to Steve Brotherton's Continental Imports and let them look at it for me.
Thanks, again, for your help and information!
John Daly