aceclimber722

I am new to the world of MB's and recently picked up a C55. The one thing that is an issue though is the Duo Valve. After reading a few threads about it I think I either need a new one or rebuild the current one. My question is where in the engine bay is it?

aceclimber722

Anyone? Charleston heat and humidity is terrible and would like the chance to fix it before taking it to the dealer and paying an arm and a leg.

mikekuriger

I don't know what a duovalve is. A quick google seach turned up this thread, and another about an A/C part. I've never worked on the AC though.

~mike~

aceclimber722

From everything that i have read it is the reason why i am getting luke warm air out of the drivers side vents and nice cool air from the passenger vents. I have tried to reset the AC with holding down the two buttons but that did not fix the issue.

91RS

I'm confused as well. Are you talking about the actuator for the temperature valves (doors)? That would be inside the car under the dash. However, are you sure the car is full on refrigerant and doesn't have a leak somewhere? I worked on a Cadillac that had a leaking condensor so it was getting low on refrigerant and the entire evaporator core wasn't getting cold. It just happened to be the side that sent air to the left side so the right side wasn't as cold.

aceclimber722

No I am not sure. I assumed that since the passenger side was blowing nice and cold that it had something to do with the way it kept the temps different per side. I am going to check that this weekend.

aceclimber722

Update:: Approximately 1lb low on R134a. Filled up and hopefully not a leak anywhere. Blows nice and cold across all vents.

billapex

My '05 C55 is exhibiting this same symptom. Before I take it in to have the refrigerant level checked, I'd like to tap on the duo valve. Does anyone know where it's located on a C55? (Thread search revealed nothing C55-specific, and I can't find it under the hood.)

Bill

billapex

Just wanted to give an update for future searchers on this subject. I took it to an independent shop, and they said the compressor had a very tiny leak. Rather than spend the $1,800 they wanted to replace the whole system, I just had them fill it up, as it was down to 0.9 lb. from the 1.9 lb. contained at full capacity. Blows cold, both sides cooling equally, and let's just hope it takes me through the AZ summer (116* today!).

Bill