Heater A/C Blower Motor Turns On After Car is Shut Off
 

Anyone?

I would bet you have the "Rest" feature on, which allows the climate control fan to run for up to 30 minutes after you turn the car off. It os a feature to help keep the interior conditioned if you are just running into a store for a short period of time. When you turn the car off, see if the REST light is illuminated (on the a/c controls). If so, just press the rest button and it should turn off the feature.

There is another thread on here somewhere about this topic. I have found my HVAC blower running occasionally after I left the car.

I believe that the answer was that the system is designed to run a little bit after the car is shut off to avoid mold/mildew in the cabin filter and this was due to customer complaints about smells.

Sounds like you might already have things figured out. I can't offer any more help than what you probably already know, but is there a relay for the blower motor? It sounds like a classic symptom of a stuck relay. BUT... maybe it's built into the motor assembly? I don't know that answer - just that maybe with some research/googling/checking fuse & relay diagrams, you can see if it would end up being a simple $15 relay.

This happens on our 2010 GL450 alot. I'm convinced that it's intentional - maybe used to dry out the air box. For us, the blower has kicked on 30-45 minutes after the truck was turned off and locked, with no keys in the vicinity. It has never caused an issue with the battery though.

My 2011 GL350 does this also. I went out to the garage one night to get something and heard a fan running. Snooping around I heard the sound coming from the grill on the hood (passenger side). Fan was running at slow speed. I am wondering if it is drying the evaporator out to keep an odor from forming? I live in a hot climate, so using the AC alot.

There is a setting in the AAC to run the fan to dry the evaporator off after the veh has been shut down for a while, it's supposed to be to prevent the moldy smells they get.

If you have the a/c off when you turn the truck off it shouldn't happen. But it's on purpose. Not for 3 hours though, that sounds bad.

Help!
 

okay so I am having this EXACT issue with my MB ML350 and I know just about nothing about cars lol. Can you tell me what wire you pulled to keep your car from dying? I am getting it looked at but until then I need to know how to prevent it from dying when I go to work.

I now have the same problem in my gl550 2008. Wondering where you got the part and what is the part number? Also how did you find out how to replace it on your own?

Thank you

Its very easy. Look at the video below.

how to replace it:

used part:

https://www.ebay.com/itm/12381655370...oAAOSwH51dkwTV

Thank you! Much appreciated

Yw. Let us know how it goes

Blower not turning off
 

Hi I also have the same problem with my 2008 ML320. Over Christmas the battery went dead and as soon as I put it on charge the Fan came on and won't turn off even when the car is off. I tried the rest button but that just turned it down for about a 2 minutes and then the red light went off and the fan turned back on. I left it for about 3 hours and it was still going. At the moment I am having to pull the fuse get time. Please can you provide instructions on how to check the resistor in the Blower motor?

The resistor is inside the blower motor. Watch the video above at 6 minutes and youll see what it looks like. Youre better off replacing the whole blower motor.

It helped me
 

After FAN resistor replacement FAN remained on. So now I have discovered a reason and REST feature didn’t know about at all

blower motor
 

Sorry I am late to the party. GL’s and Ml’s can have a moisture problem in that area. I fixed a few by taking the blower motor unit out and popping off the control cover. You will see green moisture mold .. use electronic spray cleaner.. you might be able to save it. I have extended the life of a few and than eventually replaced the whole unit. Some of my SUV’s have been dry and clean while others are wet ..my 2009 ML350 is the worst… I can pull the motor and replace in less than 45 minutes ..Bill
The green mold causes a short from the power supply to the control unit allow it to run and eventually NOT run.

blower runs continuously
 

I thought I would pass this on for what it might be worth. 2008 ML 550, blower runs with the key off. Next morning a dead battery. Happened 2 x. Removed the blower motor and was searching E-Bay for a replacement. Prices stated at`$400 and went up.
Used were $65 and up. Thought I would change just the board since the blower was running which meant it's ok. Removed the blower, area was dry and removed the 2 screws holding the cover in place for the regulator board (its not just a resistor, its a full board with many components) .
I saw the typical corrosion, but also noticed the board is also conformal coated. Even if were wet, there should be no impact. Then saw the issue...which might be the problem with most units. The regulator board is connected to the blower with 4 spade lugs. The board just pushes in place. No hoild downs, screws, anything..just held in place. The spade lugs and connectors are not conformal coated and have very small surface area for the high current connection. They are made from the same metal as the contacts in the tail ight sockets. Cleaned the lugs and the removable connectors and everything is fine.
The lugs and connectors were my problem. Hope this helps...

I have the same issue on my 2007 GL450. It goes like this. I turn off the ignition, everything powers down, then 10 seconds later the fan kicks on and stays on until the battery is drained.
I am no electrician, but it seems to me that the only way the fan/resistor could short out and keep the fan running is if it had a CONSTANT 12 volt power source . I don't think there a constant 12 volt power to the fan, so what is telling the circuit to send 12 volts power to the fan? Is there a switch or relay somewhere else that could be faulty?

There is a constant 12 volts to the blower motor via the separate 2 wire connector. There are 2 connectors. A 2 wire heavy connector for the 12 v and a small multi wire (I think there is 8 wires) connector. The blower is switched on/off by the CAN bus connector to the PCB.

I think you are looking at this that it turns on/off the 12 volts...The 12 volts is always present. The blower is not shorting, there is no relay, the b,lower is inadvertently turned on by the PCB.
The PCB is not a "resistor". Its a data (CAN BUS) receiver that turns the blower on/off, controls the speed, etc.

There is a constant 12 volts to the blower motor via the separate 2 wire connector. There are 2 connectors. A 2 wire heavy connector for the 12 v and a small multi wire (I think there is 8 wires) connector. The blower is switched on/off by the CAN bus connector to the PCB.

I think you are looking at this that it turns on/off the 12 volts...The 12 volts is always present. The blower is not shorting, there is no relay, the b,lower is inadvertently turned on by the PCB.
The PCB is not a "resistor". Its a data (CAN BUS) receiver that turns the blower on/off, controls the speed, etc.