heater fan fuse 1985 300 TD

I have and run for the last ten years a 1985 300TD wagon, about five years ago I replaced the heater fan motor. Now the fuse seems to be blowing frequently. Sometimes I can get it to last a few days, then only a half hour or so. I did notice in the fuse panel someone before me, conveniently painted a little red dot by the heater fan fuse. The fuse in there is a blue one and that's what I've been replacing it with.

Thanks,
Jonathan

PS: Thanks for a great site and source for parts, I recently bought the lube kit and gear for the sun roof in my 300D sedan, it now works great. Couldn't find that gear anywhere till I found this site.

Forums

Body and Interior Specific Aid

Chassis Model Number

W123

Causes

Hi Jonathan, I suspect that your motor is shorting internally. There is also a chance you could have a bad wiring connection someone in the circuit - but most the time it turns out to be the motor. Get under your dash on the back side of the fuse box and check for indications of burning at wire connections. Kent

fan motor

Well my wife took the car to work today and no complaints! Not yet... but I do need to resolve the problem. If I find my connections in good order, would you recomend replacing the fan motor or a rebuild?

1980 300D very similar problem

I have a 1980 300D sedan with a very similar problem and this thread seemed like a good place to post.

First a little history:
I bought the car this past November. When I bought it, only the defrost worked. However within a few days, even the defrost stopped working. The blower motor would not run. First I checked for burn marks at the motor wiring harness and found none. Then I tested the motor itself by applying 12V directly to the contacts. When I did that, the blower motor ran just fine. Just yesterday, I replaced the climate control servo and the climate control amplifier with the hope that not only would the blower motor start functioning properly, but that the other heat settings would also work properly. Unfortunately, that was not the case and I still have no blower.

However since replacing those two parts, I now have a consistant error that I did not have before. When I push the DEF button on my climate control, I immediately blow the #10 fuse. Since everything else seemed to my untrained eyes to be okay, I removed the climate control unit from the center console. Upon inspection of the climate control unit, I noticed that the green wire (DEF) is blackened where it plugs into the the button connection of the console. ( I would post a picture of this, but I am not sure how to or if it is even allowed.)

My question would then be is the burn mark on the green wire indicative of a short in the CCU and if so, is it something I can repair?

Thanks for looking and for any suggestions that may be offered.