1997 ML320 Climate Control

[xyourobob]

My ML320's climate control is not working properly. It appears one of the doors within the vent system is not working properly and unfortunatly it's not allowing the AC to come through. It's an inconsistant problem. Today I put the a/c on and it was working fine until I heard something like a vent door closing in the dash and then hot air was flowing out of the vents. This did not change when I turned off the AC and just tried a cool vent setting. It's always pumping out heat now. Any idea where I should focus my repair effort? Thanks Bob

[skiier3_9]

What part of the world are you in? I was under the impression that the ML wasn't available until 1998.

[xyourobob]

Thanks for any advice

[stevebfl]

Unfortunately it sounds like a blend door actuator motor problem. Actually quite common. Cheap part with a cheap plastic clockwork mechanism that require removing the upper dash to access.

I would try to drive it with a diagnostic tool first and verify the activity, but the part does fail regularly.

[xyourobob]

Does this diagnostic tool plug in somewhere under the dash? Where would I get one and how big of a job is removing the upper dash in this vehicle?

[stevebfl]

Yes, the tool plugs in beneath the dash, near the drivers kickpanel above the emerg brake. Bootleg versions of the tool can be had on ebay, but the real thing is purchased through Mercedes and the lesser priced version is only $10,000.

Replacing the mode door motor is about a three hour job.

[xyourobob]

Thanks for your help.

[xyourobob]

Do you reckon this is a fairly easy project or would I need special tools outside of standard screw drivers and the like. I have worked on autos all my life however I have never removed a dash. I'm considering undertaking the project myself. Thoughts?