The car is a 1979 300SD, 160,000 miles residing in New York City. Here is my problem (again!!!) My blower motor finally died. I was doing the bump and run for a few months. I know about the possible remedies for repairing (replace brushes etc...) but I decided to go new. I purchased a brand new Bosch unit. Did the swap and all is good. Worked for about 2 weeks and then I started blowing the #3 fuse (Blue-25amp). Replaced the fuse and all is good again. Fuse blows again a few days later. Replace the fuse and then as soon as you hit any button on the ACC the fuse blows. I call the parts person and tell him my situation. He tells me he will send me a new unit. I get the new unit do the swap and all is good again. This morning on my way to work went to hit the auto low on the ACC for some heat and the fuse blows. What is going on here? Is it possible the car is throwing to much juice to the blower motor? What can this be? Has anyone else had this problem in their 116? I can't understand why this problems occurs after about 2 weeks of normal operation.

NYDIESEL,

That is strange that the same problem has happened again. Cars don't "throw juice", though. The only way that the car could overload the blower motor is if there was an over voltage condition. But other things would burn out first such as light bulbs.

Are you sure the motor wasn't stalled by the fan rubbing against the housing? If a motor is energized in a stalled condition, it could be damaged.

P E H

Look for a short in the resistor pack for the fan speed control. I'm not sure where it is on the W116, but it's a set of nichrome wire coils somewhere. If one is shorted to ground, it will blow the fuse when it is selected. Various resistors are used to limit the current to the fan, controlling the speed.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

NYDIESEL,

Hook the blower motor to a 12DC voltage source. A battery charger would be good because it has an ammeter. Let the motor run for a while and observe the ammeter and see if the motor ever pulls enough current to blow a fuse.

P E H