JimPap

My A/C has gradually not cooled down the car as fast as before so I took the recently out of warranty C300 to the dealer for repair. As they replaced an "o" ring last August, I thought it might be related or that they had missed it and could get it repaired without costing me.

They say that its an "o" ring on the compressor and that it wasn't the same one that was repaired last year.

Originally they told me that the repair would be $534.74. After I complained a little, they told me that they'd split it with me and it would cost half that which is $267.37. To me, that's still outrageous. The "O" ring was backordered to Germany and it may take a couple of weeks to arrive. They did add freon to the system so for now, its cooling fine.

Has anyone else had this problem and if so, what was the resolution????

Has there been any special notices allowing out of warranty C300 2008 to have this repaired at MB's expense????

JoeVal

If your car is out of warranty, the o-ring failure is probably due to the system not being used during long periods of time in the cold periods. An almost universal warning on A/C is the fact that seals would deteriorate when the system is not turned on at least 10 minutes every 2 weeks. In these systems the fact that they had to add freon means there was a loss. What I would do to open the umbrella before it rains again is to change all seals, instead of only the failed one, and any joint or hose which looks suspicious. Afterwards, there would be no reason for future failure by developing a leak as long as you keep the system lubed by running it as I mentioned before.

I don't seem you are going to be happy this time. Sorry.

nyca

True, but you do run the compressor in the non-summer months to run the window defoggers - so it gets used there.

albert101

The cost of the O-ring is pretty much nothing. What you're paying for is the labor. If the W204 is anything like previous Benz models, the whole dashboard needs to come out in order to access your AC unit. That's where the expensive labor comes in.

JimPap

joe,
nyca is right in that when you run the window defoggers, the compressor gets used. Also, I think I recall something about the compressor is constantly spinning and in its design, they're some kind of vains that change position when its called upon.

albert,
Are you saying that the compressor is somehow under the dash? So what's that compressor looking thing with the freon lines between the engine block and the radiator?

RLE

So much confusion....

The condensor is in front of the radiator. The evaporator is in the cabin behind the dash. The compressor, driven by the multi-rib belt is at the lower left of the engine. The clutchless compressor turns all the time and the R-134 refrigerant flow is regulated by a "computer" which varies the angle of the swashplates inside. MB has used swashplate compressors for at least ten years which eliminated the compressor clutch which was another failure item. Therefore, you cannot feel the compressor "kick in" because it a slow process.

Anything else?

inactiveuser1019

I've noticed it's also a slow process when I turn it off, where it can sometimes still cool for almost five minutes.

Diesel Benz

But this is a different slow process. The fact that you get cold for some time after the AC has been turned off is from the freon pressure already built up, once the pressure is getting released at the evaporator, you still get some cold even if the compressor is not running any more.

The compressor starts and stop slowly when compared to a clutch but is still fast compared to the time it takes for the pressure being released at the evaporator.

RLE

According the service manager at my dealer, it can take several minutes. In any case, it's normal.

nyca

Perhaps these new clutchless compressors are different, but on the "old" systems it was always a good idea to disengage your AC (not the fan) about a minute before you knew you were arriving at your destination and shutting the car down. I still do it even in this car as a habit.

Diesel Benz

This is a good habit to dry the heater core, not to improve the O-ring lifetime. Actually current models do it automatically, after about 30 minutes the blower runs for a while to dry the heater parts (the result sometimes is foggy windows inside).

Diesel Benz

Can you clarify what are you referring with "it"? It can take a long time for the AC system pressure to be completely released. This means that the AC system makes noise quite some time after the engine has been switched off etc. Dealers have bulletins that explain this and this is what they are supposed to explain to customers.

But I was after the on/off switching time of the AC compressor itself. I was not able to find real figures for this but it really does not take minutes to turn the swash-plate from one end to the other, preferably a few seconds.

I could try this with Xentry diagnosis, it allows direct control of the compressor cooling power and reports the actual values for refrigerant pressure and evaporator temperature readings.

RLE

This is a trivial point, but MB hasn't used freon since the '80s. At least. Even my '95 C280 used R-134A.

Carsy

I think Freon is being used as a generic term.

Diesel Benz

Sure, my mistake (not the first, not the last one). I don't think this makes a difference with the content of the comment anyway.

JoeVal

Another point regarding O-rings is that these are not supposed to be neoprene or buna-n standard O-rings, but O-rings to keep the freon seals tight. These O-rings are not found everywhere and the fact that they bring them from Europe is a cost adding feature that happens not to research a US source for replacements which can be poor performing.

JimPap

Never the less, I don't really think it should have gone out this early and if since it did, MB should be picking up the tab, not me.