Originally Posted by JCFans

Hello. I have a 2005 E320 with four-zone climate control thermotronic. The weather has been getting warmer here in Toronto so today I decided to turn the A/C on.

What I noticed is that ONLY HEAT is coming from all the grilles in the backseat even when the setting in the backseat is set to 12C or to all LOs. There are 4 grilles in the backseat (2 in the middle, 1 in the left vertical pillar by the door, and 1 in the right). Cold air is coming through all the front grilles.

What is going on??? I had to manually turn off (block) the hot air from coming through to the backseat passengers to accommodate them as it was getting really hot.

Any thoughts?

Originally Posted by JCFans

Thanks so much!!!

Any idea how much would the parts cost and where to get it from? Alternatively, my next service is coming up soon. How much would this cost approximately if we do this in-house at the dealership? Is this covered by warranty?

Originally Posted by Benz-O-Rama

If your car is under warranty, of course it would be covered. As far a price for the part, read the thread I linked you to. The part number is in there.

Originally Posted by JCFans

Thanks! I realized that the first time around. I don't know anything about cars and therefore I'm just a wee bit confused as to how to find out how much this part costs, apart from knowing the part number.

Additionally, on a more interesting note, this problem has resolved itself by this morning. I turned the A/C on and it releases cold air. I switched to the heater and it releases hot air.

Is this normal or should I be worried about relapse?

Originally Posted by JCFans

Thanks! I realized that the first time around. I don't know anything about cars and therefore I'm just a wee bit confused as to how to find out how much this part costs, apart from knowing the part number.

Additionally, on a more interesting note, this problem has resolved itself by this morning. I turned the A/C on and it releases cold air. I switched to the heater and it releases hot air.

Is this normal or should I be worried about relapse?

Originally Posted by Benz-O-Rama

Yeah, I bet it's gonna need to be changed soon. If it were me, I'd wait until it did it again, then swap it out. But if my car were under warranty, I'd take it in and have it replaced now. Very common problem on these cars and the dealer shouldn't hassle you about changing it.

Originally Posted by JCFans

Thanks, Benz-O-Rama! Going back to my original question, how much would the dealer charge me approximately to have this replaced? I just realized that my warranty had lapsed a few months ago. I'm based out of Toronto.

Originally Posted by jeffsnavely

The part was $42 with MB club discount. The dealer wanted $450 to do this job, so it's well worth the DIY.

Allow about 2-3 hours for this job. In another thread someone claims it only took 35 minutes, but I don't know how that's possible, even for a pro.

I have very small hands and it was very hard to reach things - if you have very large hands you may not be able to get this done by yourself.

--Open the hood to the fully open service position (push in the tab on the interior side of the hinge, one on each side of the car)

I had a very hard time prying the 4 black plastic rivets out, I ended up destroying them so I need to buy new ones (you can live without them for a few days).

The metal clips: pulling them with the coat hanger worked easily for one of them, but the other two I had to pry the end free with my finger to get it started which raised up one side a bit, them pull with the hanger.
The one facing towards the passenger side was not visible until I climbed up onto the car and stuck my face right down in the area.

After removing the first hose from the engine bay, fully remove the circle rubber grommet between the engine bay and the firewall area - this lets you reach in through the hole to maneuver the part.

The hose clamp is the hardest part - it takes a lot of force to fully open it, so needle nose pliers didn't work very well. Use a small locking pliers and grab it vertically from straight down. Do this after unclipping the 3 metal clips to the other hoses, as you can them move the part around to get it in position.

I moved the hose clamp back a few inches then removed the pliers - you need the space to reach in to pull the hose off. One technique is to hold the part in place by reaching through the circle hole.

I undid the electrical connector last as it was hard to get to otherwise.

When installing the new valve:
-electrical plug first
-large hose with hose clamp next (you need to be able to brace it against the driver's side of the car, against a tool handle etc).
-the two outlets towards the rear of the car next (leave the clips closed and just push them as mentioned about - it did take a lot of force to get them to click into place)
-reinstall rubber circular grommet
-engine bay hose

Originally Posted by JCFans

Any idea how much would the parts cost and where to get it from?