Heater blower motor repair

WhiteNBlack08 · 10-16-2009, 06:53 PM

I decided to post this little tutorial so others don't go through the frustration I did tonight. Recently there have been several posts about heater blower motor failures. I joined those ranks last week. My blower was operating intermittently, and when it did work, I had to have it on high to get any air movement at all. I call my local smart center, and a new motor is $287!

Some have had switch failure, and some have had the resistor burn out. I traced my to the motor itself. I could wiggle the wires going into it, and change the speed of the motor. First off, after wasting 1 1/2 hours trying to figure out how to pull the heater assembly, I finally figured out it takes 2 minutes to pull the motor. Below, see the motor locaton on the heater assembly:

Next is a picture with the blower removed:

remove the connector, and simply turn the motor assembly counter-clockwise until it releases. Then pull it out.

Here is a picture of the motor out:

Remove the torx screw on the end, and you can pull the motor and fan wheel out of the plastic housing:

When I pulled the motor, the commutator was completely black. There are little white rubber covers over the brushes, pull them off, then you can move the brush springs out of the way, and clean the comm up. I started with some 400 grit wet or dry sandpaper, then moved to 600. In the next picture, you can see that the comm cleaned up nice. The motor shaft sticks out the end of the blower wheel about 1/2", I chucked that up in my cordless drill, and used that to drive it while I used my finger to hold the sandpaper against the comm. Blow it out well when your done.

Re-install in reverse order.

My fan now works perfectly, and I saved myself $300 and a 4 hour round trip to the dealer.

I'm out of warranty, that's the main reason I did this repair myself. Hope this helps some others on the forum.

By the way, these motors are built with bushings, so while I had it out, I oiled both ends as well, seemed to help.

Carlarm · 10-16-2009, 07:03 PM

Thanks for the photos. My blower was replaced under warranty because it was making a lot of noise. It was interesting to see how easy it is to remove it. I've also fixed motors by cleaning up the commutator. It should be as good as new now, except it begs the question why it got gummed up so quickly.

WhiteNBlack08 · 10-16-2009, 07:26 PM

I agree, it concerns me that it blackened so quickly, I know when I pulled it out, the motor was very stiff to turn. I put a couple of drops of air tool oil on the bearings, and it seemed to free it right up. Maybe that is the culprit? Maybe the supplier(Behr) needs to improve their lubrication at assembly.

chieftmc · 10-17-2009, 08:53 AM

can you put this in the "Tech Library" ??

TMACK · 10-17-2009, 10:04 AM

Superb post. This goes to the head of my home brew technical manual.

Hey, now THERE's a good idea.

Why has no one in this community thought of compiling, editing, printing with full disclaimers and marketing the profound, collective wisdom of SOCA?
Given nothing else is available, (beside Evilution's online library), I'd pay good money for a hard copy, forum generated TM.

WhiteNBlack08 · 10-17-2009, 10:35 AM

Thanks for the positive feedback, I hope this helps a few people out. There is a way to get a complete tech manual for the smart see the following thread:
Mercedes WIS (Workshop Information System)

One note though, part of the reason I had difficulty, is that I bought the DVD and installed it, but for some reason my 10 year access keys are no longer valid, and I have not gotten a response from the company yet as to why. I have sent them several e-mails, with no reply to any. I'll buy another set of keys(they are only $10) but if I pay for 10 years of access, I expect 10 years. I'm sure that if I had been able to access the system, I would have quickly found out the proper way to remove the blower.