Since I was having seizing problems with my heater blower this past winter, I decided to try to investigate the intake and see if there were some obstructions. The fresh air intake is at the base of the windshield under the passenger side wiper, so it is possible that leaves and other debris could have fallen in and gotten trapped in the fan.

Incidentally, the airbox sits above the battery in the engine compartment for my C350W4M, so this should also help with those who were asking where the battery for their car is. (Although, I understand that the diesel cars have their battery in the trunk next to the spare tyre)

NB: As we are working within the engine compartment and near electrical systems, please take safety precautions. Make sure the engine is off, the car is parked safely with emergency brakes engaged, you understand what you are getting into. If you have any doubt, please leave this to the professionals...

So, start by opening up the engine bay (you may want to open up the hood further to give you more working room) and locate the black plastic airbox that is at the base of the passenger side windshield, next to the jump star connector:



There are three metal clips holding the box to the car at the trailing edge (closer to the windshield), this is the one on the right, which you have the swing rightwards, retaching the clip from the box:



The one on the left side of the box swings leftwards, detaching from the box:



Here is the one in the middle which you have to pull upwards on the car (far) side, as the clip is attached to the box:



Now pull the box gentle towards you to pull it out from the hoses, about 1/2 inch, and then upwards, in a "J" motion. Very little force is necessary to remove the box. Slowly work it loose if it is sticky due to the dirt and grime. Here's what the detached box looks like:



And turn it around to see the intake (now on the left), and the supply which feeds a small fan that is in the passenger side dash:



So the air just does a U-turn in that box. I found no filters in the box. Mine was a little wet inside because I had just washed my car and water must have ran down from the intake at the wiper into the box.



And on the car side, there is the intake on the right. The air is drawn down from the mesh grill under the wiper down and into the box. Then makes the U-turn around the box and towards the dash (left side) where there is a fan (white fins) which sucks the air downwards.



And it looks like there is an air return just above the fan as well to mix the fresh air with the interior air.



And of course here is your beloved battery:



I also found a little rubber flap on the intake side, possibly where the water/dirt should have washed out, if fallen into the mesh grill.



Reverse the procedure to put the airbox back into place. Note that there are two tabs at the bottom of the intake and supply hoses that need to match up with the airbox.

 

The dust filter is located just under the fan unit, remove the panelling below the glove compartment and slide two plastic tabs outwards to unlock the filter, then pull it straight down.

You might want to check it out, I have seen filters covered in seed pods and even soaked in water.

 

Vic Viper - Thanks for the tip. I will definitely take a look at my filter. My primary concern was that there was something lodged in my blower causing the seizure. Or that there was ice damage to the fan. But I found neither... So maybe it was just a cold weather issue.

 

peabers, did you notice rust on the metal rod of your intake fan?
I opened mine last week and was a bit surprised to see the metal rod is a bit rusted..

https://mbworld.org/forums/c-class-w...er-change.html

Here is the link for cabin filter removal...
How often do we need to change the cabin air filter?? I had sour smell from my a/c a couple weeks ago..
The smell has since disappeared after I let the car dry out a bit..but was wondering if I still should have my a/c serviced..

 

The fan looked really clean on my car... I was more concerned about warped fins though. There was a bit of dust so I wiped it off with a damp cloth.

There was a thread about the foul odor on this forum... likely culprit is moisture on the condenser causing mold to grow. Run the heat for a while to dry out the condenser. If the odor comes back take it to the dealer and have them spray it with a cleansing solution.