240D 115 blower motor problems

[AlexCole]

Not having any hits in the Diesel Discussion, so figured I'd post it here, too:

I think I have a serious (serious=PITA to fix) problem and wanted some input. I have searched the archives and everything I have read about the blower motor for the fan indicates it is difficult to get to, as in the fan is hung up and the car is built around it kind of difficult. I have ordered the Service Manual on cd from MBUSA, waiting for it to come in.
Here is my problem: In the defrost/heat mode, the fan will not blow on any of the 3 switch settings. In the A/C mode, the fan will only blow (and blow cold) in the #3 (highest) setting. Problem just happened one day, as in everything was fine one day, broken the next, with no decline in function over time.
My question: Is there hope that this might be something else besides the fan motor or brushes?
I have seen alot of talk previously on brushes needing replaced, and people doing it with non-MB brushes that they picked up from Ace or the vaccum cleaner shop, etc, but I'm pretty sure those were 123's.
Thanks, Alex

[Kpmurphy]

over the weekend I just got a 115 240D 1976 stick shift.
I was talking to a friend over the weekend, if i remember corellcty I think he told me that the blower moter was turned on by vacume. Somone out there is this corect?

I was adjusting my valves for the first time so i was not paying much attention about the blower moter.

If you find out post it so i can fix mine
Kevin

[250 Coupe]

This is based on assuming that the fan setup in a 115 is the same as in a 114.

The heater blower is just under the aluminum cowl at the base of the windshield. You can just barely see it if you pull the cowl off. Check it to make sure it spins, sometimes they freeze up.

The AC blower is in the base of the center console. It's not known to fail nearly as often as the heater blower.

The change over switch is mounted to a vacuum actuator located above the throttle and toward the center of the car.

To me, a loss of lower speeds means that the blower resistor has gone bad. IIRC, it's mounted partly in the cowl area, just to the outside (inside?) of the master cylinder. Wires come up the firewall and terminate in a four (or six?) pin plug that looks like it's plugged into the firewall. If it goes open, you'll lose some or all speeds.

No heater blower at all means either the motor is not working or the change over switch is not working. How is your vacuum pump? Low vacuum might not let it travel far enough to make the switch.

I'm headed off to bed now.

Michael