Hi all,

I've got a W210 M111.957 engine.

Problem 1)
Recently I noted that when I press the recirculate button, I no longer hear the flaps closing. Seems like the motor controlling it is failing. I opened the external air intake vent from the engine bonnet and noticed that when I pressed the recirculate button, the flap moves very little.
So I searched through the forum to look for answers. However, I didn't see much discussion on this flap thingy. As it's always very annoying to smell the fumes (city living), I decided to dismantle the rod holding the flap and sealed up the flap. However, I then realized that it was worse. Now, air from the aircon cabin vents isn't really blowing much air out. Even when I pressed the recirculate button, you can see the LED light but it's still not drawing air from my underseats vent.

So this means there's possibly 2 flaps? 1 for external air and 1 for under seats vent? And this recirculate motor controls both flaps at the same time?

If my guess is correct, can someone advise me where is the flap for the under seat vents for recirculating air? I've already sealed the external intake flap and it seems like the blower is still drawing air from outside, otherwise not much air is coming out from the aircon.

Problem 2)
Duovalve. Once I noted hot air was coming out from the right side. cold on the left. It was only intermitten and the problem went away after turning off/on the aircon again.

But when I looked through this forum, I found a few pictorial DIYs and so I went through the steps to check it. Opened it, found the pistons working fairly ok, and so I assembled it back. Didn't really remove the whole thing though. Ended up now the right side is always hot air and no longer intermitten. Also I noted the duovalve was leaking coolant even though all the torx screws were tight. So I figured out that maybe the gasket was out of place when I assembled it.

So I took it apart again and this time I took a closer look at the pistons and found that the stains on it, was actually dirt! With a flat screwsdriver + RP7 spray, I removed all those gum and it looks much better and it's more smoother now going up/down. But I noted 1 piston had some corrosion on it. Cleaned the small arrow looking plunger as well. Fitted everything back carefully. Noted the electronics part had some muddy looking stains so I used some RP7 spray on it as well to clean it. Could be due to the coolant leaking earlier due to my bad assembly. Anyway I also sprayed some RP7 onto the electronic contact hoping to clean it also.

Assembled everything back. Turned on the ignition and was shocked to see some sparks! oh no! Could be due to excessive RP7 residue and there were some burnt smell. I quickly turned off the ignition and dried the contacts a bit more and waited for the RP7 spray to evaporate more. Connected the contact back again and turned the ignition again. This time, no more leak and no more sparks. And best of all the right side aircon is cold again! Hurray! But I wonder how long this duovalve will last after this servicing as there were some corrosion on a piston that makes it quite rough. But it's really great to have aircon back on again. Just thought of sharing this here so that other forummers will not be so careless like me to leave so much RP7 (or similar) spray on the duovalve.

Thanks.