AC/Heater diagnosis...1982 300D - PeachParts Mercedes-Benz Forum

300DPETE · #1 11-02-2005, 12:41 AM

1982 300D

Update on my AC/Heater problems...it's a little better since I changed a blown fuse, but:

When I turn on my AC or heater, it sounds like the fan in the blower is fighting to run properly. It speeds up, then slows down, "sputters," etc.

Within the last year or two, the blower was cleaned and the brushes replaced by the previous owner...should I check to see if this was done properly? Sounds like it's the blower to me, but maybe I'm wrong.

Thanks,

Pete.

bhanson · #2 11-02-2005, 07:19 AM

Sounds like the blower, but it could be an erratic connection as well. Test your current at the fan if you can, and see if it is connectivity somewhere. Could trace back to the ACC. On the other hand, if you jump the fan straight to 12v, and it is still acting up, it's the blower motor itself.

300DPETE · #3 11-02-2005, 08:11 AM

Ahhh. You're one of those "common sense" type people

Thanks, bhanson.

Pete.

300DPETE · #4 11-05-2005, 02:03 PM

I recently posted this on a new thread, but forgot that I had this one going. Here's the resolvement of the issue:

So, I decided to check the heater blower on my car (1982 300D) even thought the previous owner said that the brushes had been replaced in the last couple of years.

Well, when I took out the old brushes, they were just tiny stubs with copper wire stuck to them.

....but wait, there's more!

As I was inspecting the unit, turning it around, two more pieces of brush fell out on each side (3 total on each side). Someone had taken the stuby remains of other brushes and packed them in with the stuby brush with the copper wire attached in the back of each "pack." I could tell that they weren't each just one that broke into three pieces because each piece had the grooved and curved end, indicating contact with the center post of the motor.

I'm going to give the previous owner, because he's probably taking his daughter's 124 to the same mechanic who did this "repair."

No wonder the darn thing kept on sputtering out.

Runs like a hurricane now (as long as my "expert" soldering decides to hold out).

Pete.

bhanson · #5 11-05-2005, 08:15 PM

Glad that worked out. I actually went through a multi-stage replacement that ended up much the same way. Started when my aux. water pump used the etching on the ACC circuit board as a fuse. I soldered all that back together. Turned out I was still blowing fuses. The motor turned out to be aftermarket and really stiff and worn. Couldn't replace the brushes easily. Finally, I found another 300D wrecked in the woods through a friend's connection, which had a good blower, but needed brushes. The brushes were easy to replace, but one side of the end-cap wouldn't reseal to the motor, and I ended up soldering it back together. End result is I have good heat again, although I'm still looking for an auxiliary water pump. The one off the same junker was just as dead as mine.
Ben