I have 2007 ML 320 CDI Sport with an interior fan issue. The passenger compartment fan continues to run after I shut down the engine and take out the key. Recently had an ice storm and had to run the defroster for an extended period of time, otherwise operation has been normal.

 

Are you sure the "REST" button is not stuck. This is to actuate the fan and circulate warm air while car is off.

 

you ran the climate control on max with your hood covered in snow. now your blower motor is wet. its a poor deisgn. when the hood is covered in snow so is the fresh air box inlet.. when you put your air on max is sucking in melting snow, theres a voltage regulator installed on the blower motor and now its wet causing the blower motor to stay on and draining your battery.. replace your blower motor and cabin filter cause that is wet too...clean your hood when running your climate control !!!

 

AMGfan84 - you hit this blower fan (pun intended) problem square on the head...

OP - john.head - thank you so much for posting your issue.

I recently purchased a 2009 GL450. (less than 2 weeks ago)... Like the OP, we had a severe freezing rain/ice storm just a few days ago here in South Carolina. My garage was full, so the GL was parked outside. It was covered with a layer of ice in a matter of hours. No problem, I thought - this is a Mercedes...

I fired up the GL to defrost - let it run at least 15 minutes with the heat wide open. Broke up the layer of ice and began testing the 4MATIC in my neighborhood. The next day, the battery was dead. I quickly learned how to ratchet the door open, charged the battery, fired her up - and then the heater would not shut off after turning off the engine!!!

Searched and found numerous posts on regulators, resistors, blowers, etc. and this post from OP fit my scenario exactly.

Being an electronic technician - I felt comfortable removing the PCB from the bottom of the blower assembly. Sure enough, while removing the plastic cover under the passenger dash, I found a small amount of fresh, clean moisture below the nonwoven insulating material.

After removing the PCB from the blower, I noticed some corrosion. Cleaned it up with contact cleaner, dried it good, re-installed. It no longer run after shutting off the engine! Tried again, and the problem returned......

We ran the vehicle for 2 days and noticed that eventually, the motor did not continue to run after shutting off the engine any more. I'm not 100% sure if it was my cleaning the PCB - or the heater air drying out the regulator - which I have not pulled or examined yet.

Pictures attached. Water corrosion / traces can be seen on the closeups.

I've only pulled the PCB from the bottom of the motor - nothing more. Can anyone kindly point me to the location of the regulator (resistor?) module that apparently has the aluminum heat sink? I'm thinking there is some water corrosion needing some cleaning there too.... If water has gotten in there, I will find the evidence...

Martin