markloch

My 03 ML's cabin air flow has always seemed wimpy compared to my 02 CLK and 98 E. The CLK and E blow tons of air, ML not so much. Cabin filter swapped when I bought it a year ago. I've chalked up to it being an ML though have always wondered if air distribution isn't quite right.

Very recently the amount of air flowing through the three center dash vents changed: passenger side flow is high, driver's and middle are a comparative trickle (when selector is on center vents). It used to be balanced. I haven't had a chance to determine whether it's as equally one-sided at the floor and defroster vents when selected accordingly.

The blower has gotten noisier, though I'm not sure if the imbalanced air flow and the increase noise occurred at the same time ... though the increase noise does sound like a fan trying to blow the same amount of air through a more restricted outlet.

Anyway, I'm trying to understand how air distribution works on this car - anyone have the appropriate schematics, etc?

Cheers,

Mark

Maj. Dundee

Remove the Blower Motor, remove all debris and change the Cabin Air Filter.

fantasy521

I have the 02 ML 500. I remember on my third year of ownership around 2008 (my dad back then) the center aircon made this random ticking noise. I found out the blower fan? was knocked over and was touching the top.

markloch

I'll give this a shot and report back - thanks!

markloch

Not much debris - a couple of leaves that may have accounted for a slight buzz - and filter still reasonably clean (replaced about 6000 miles ago).

Messing with the air distribution dial, no matter the setting the driver's side defrost is always blowing hard, and floor doesn't blow much even when dial set accordingly, while passenger side distributes as expected, blows at feet when set at feet, defrost when set to defrost, etc.

Is it vacuum-based or electric that actuates the distribution flaps and how do I get to what every actuates the flaps?

Cheers,

Mark

Maj. Dundee

First let me say that there is no vacuum that controls the A/C-Heater System. Everything is electrical.

Secondly, from 2002-2005 ML's have an additional/separate Blower Motor behind the center vents to aid in cooling the rear passenger seating.

All defroster air is directed to the vent on the Instrument Cluster (red mark). What I don't understand is you saying, "the driver's side defrost". Do you mean the side vent?

Please re-explain your second paragraph as it is a little confusing.