W202 Niggles - help!

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Active Member
Apr 18, 2008
Hi guys, I've got a few niggles with my W202 and wanted to get your advice.

- The sunroof won't open or make any noise suggesting it's strained. Literally, press the button and it does nothing. Fuse checked. Any suggestions?

- The fan ALWAYS blows warm air. Is there a linkeage to the heater matrix that could be goosed?

- It smells damp. Are there any drainage holes I might be able to blow through? Possibly related to the above?


M :)
sunroof sounds nasty, hate those things. heat to the interior controlled by an electric duo valve under the bonnet. might be stuck open. the left and right sides of the car controlled independently by two solenoids in the duo valve. are both sides of dash blowing hot? i would start by looking at the duo valve. hope this helps.
Further to redfox advice, you could try tapping the valves with the handle of a screwdriver, this might free them if the are sticking, remember it will take several minutes for the cabin air temperature to change from hot to cold, it will not be instant. Check also the wiring plug connection that goes into the valves

Not the same car as yours but for a greater insight regarding the valves sees… http://www.mbclub.co.uk/forums/showthread.php?t=26888

Your sunroof motor has gone most likely, it went on mine and it's a big and expensive job to get it replaced.........

Mine went a few years ago and was replaced and it cost 900 quid from the stealer to put right.
If you remove the front passenger side lens light cover above the rear view mirror, (get your finger nails under the rear edge and pull down) you will see the long bulb and just beside it, a round hole into which is inserted an allan type key winder, one of these should have come with the car, I lost mine so cant describe it exactly, anyway this key will allow you to manually wind open and wind shut the sunroof. This might help you investigating the smell.

If the whole light unit is removed, the opening is quite big and you can see the motor, however I cant recall if it is possible to get your hand at the motor to have a fiddle around in the hope of getting it moving again.
Removing the light unit in itself is a tricky job as you can damage the surrounding trim in the process so it might be wise to do a search for a How – Too on this job first, there is one, somewhere.

Couple of easier things to check - for the sunroof check the switch itself - mine went and caused that symptom albeit only on the tilt opening. About £10 ish for a new one from MB or borrow one from another car - they are very easy to remove.
For the temperature control there is an air duct running from a grille next to the sunroof switch (assuming it is the same as my w124 - if not forget this) - make sure that grille is clear and not bunged up with fluff and dirt - again I had the same symptoms as you and that is all it was.

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