For almost a year my A/C had been making this slight hissing sound but I dismissed it as "normal". Wrong. At the same time, the driver's side was roasting hot outside air and the passenger side was the only one that cooled down. One day, all cool air stopped. I immediately shut down the A/C and went to the local shop here in VA that works on Benzes. ( A previous trip to the dealer in Sarasota, Fl resulted in two techs recommending a compressor after looking at it for about 5 minutes. No thank you. ) Anyway, the local shop evacuated the system and replaced a hose on the low side ( apparently the side that had some sort of connection to the driver's side ) and did a recharge. It lasted for one day. I soon went back to the shop and they did another evacuation. The mechanic noticed that there was some blockage of debris and material in the freon. Yikes! Anyway, after a second recharge it worked. I now have ice cold air, no hissing and it has been good to go for over two months now. My black on black color combo forces me to use A/C though I avoid it if possible.
Moral of the story? Before you toss $$$ at new parts, have the mechanic check for worn hoses, do an evac and a recharge. Try it again if needed. I spent about $230 for the two charges etc... Beats $1400+ for a compressor that I did not need. I hope that this helps. [8D]

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Hi,

If one side of the car worked and the other not I don't see how it could have been the compressor! So much for the MB mechanic diagnosis.

Also surprised that a recharge has cured problem permanently. How did this process REMOVE (hose) debris? May have moved it.

Suggest problem WAS debris (hissing noise) in evaporator throttle valve.

Stuart

 

Thanks. I don't know how it magically cleared it, but it did. It has never worked better. Maybe the hose had something to do with it, moreso than we both thought. I'm all about spending the right money on the car, and not spending money on stuff that I don't need. Good luck to all that have experienced the same thing that I just went throught. It's an awful feeling knowing that you may have to spend up to a mortgage payment to get your damn A/C working again.