Joe S

Recently acquired an 07 S600. On first long distance trip, noticed front of cabin was getting hot while cooling was on and in auto mode. Got so warm I was starting to sweat. Checked all settings and verified system was set correctly. Checked with Tele aid and asked to to recheck system which I all ready did. While at a stop to eat. I called dealer about the problem and they assured me they have had no problems with the a/c system. Started car and moisture was actually discharging out of the front vent something I never experienced in any car before, however, system was on max at this point, and seemed to be cooling the car. I didn't want to touch any of the settings so I left everything alone. About 1/2 later cabin started to get hot again. I manually forced the fan into high speed which seemed to help. I don't believe it is a refrigerant problem rather it seems to be a thermostat sensor type problem. Anyone experience this king of problem? I assume S550 and S600 are the same system. Thanks, Joe

RajwanyS550

on a 2007 car it can be any number of things. better take it to a dealer.

Kar don

sounds like it is low on refrigerant or leaking and the evaporator is freezing. This is why when you let it sit for a while the evaporator is thawing out and working until it freezes over again.

Dealer needs to evacuate the system and recharge it with dye to find the leak.

Joe S

Yes your diagnoses sounds plausible. That will explain water discharging
out of the vent when I turned the system on again after sitting awhile.
Many thanks,
Joe

platt-deutsch

Could be the duovalve

Diesel Benz

No. Because the 221 does not have any duovalve. It has a similar valve as on a W211, this time called "AC water valve". In early W211 cars this valve took the task of duovalves (in the sense that they used to fail ). I have not heard of similar issues on 221 cars or later 211 cars.

Joe S

Took it to a local dealer here where I'm visiting (Tysinger, Hampton, VA). They took the car in for service today...system operating properly. What they found was one of two condensate drains was clogged. This caused water to back up and then caused air flow restriction which caused the coil to freeze. They cleaned the drain, and I had an hour drive back to my daughters and system cooled perfectly. Car only has 23,000 miles, never had a drain back up on me before, but you live to learn everyday.
First Mercedes, and I was very pleased with the dealer servicing me right away especially since I was out of town. They didn't want me driving home with same problem. Can't say I was pleased calling Tele aid while driving on I95 when I was having problems. But the dealer was great.
Thanks for everyone thoughts.
Joe

Red Marko

Interesting thread, summer is almost here, everybody will use A/C to the fullest.

I too have a similar car as yours (in CL version) and I have to admit that A/C system is S/CL is NOT to MB standards.
It never died on me, although I find myself quite often playing with it.
Too hot, catching up... then too cold, adjust... and so on. It is far away from set-it-and-forget-it every American car has system.
Almost, it looks like Germans don't sweat too much, so it's not that important to them.
Let them spend one hot summer here and sweat their b@lls

emilner

Mark I agree 100%. I have remarked endlessly that I wish the S550 had an a/c system like any GM truck I have owned for the last ten years. You set a temp and forget there is climate control, it is that easy. One awesome find on my wife's new '10 Escalade- when you make a bleutooth phone call the A/C AUTOMATICALLY drops the blower speed so you can hear the conversation!!! I HATE the way you can drop the fan speed to 1 on the drivers side of the S550 but the sound gets LOUDER until you drop the fan on the passenger side. It stinks when you wish a $100k MB flagship line car could perform as good as a Chevy/GM truck...

Kar don

Nice, Glad there was no refrigerant leak. I knew it was your evap though, I've had one of those leak and thats the tell tale sign its starting to go.

QuadBenz

I recall our S550 doing this previously. It might have been a Tele Aid call, but it does do it. It also lowers the fan speed when you press the voice command button.

Diesel Benz

I've never touched the AC settings other than for learning the settings. Perhaps I use the car differently, I hardly start driving from the street when the car has been exposed to direct sun shine etc. I think US cars are set differently, usually not to save fuel and to adapt the cooling power to the actual needs but to run the AC at full power and then control the temperature with the heater while Euro cars use AC power just enough to get the car cool and the air dry enough to prevent condensation. Could this make a difference when the AC actually starts more quickly than the heater (no engine heat)?

Joe S

S600 working fine since repair yesterday, but would like to commit that system controls and adjustments are too complicated. There are numerous adjustments to the fan speeds and diffusion, not really necessary. The 07 Ls that I traded in had a wonderful system, and was very sophisticated, new Denali, while not as sophisticated you can hang meat in the back if you want to.