Blower motor quit suddenly, clues?

[JCSC2]

Driving home one day and all of a sudden the blower motor quit. It was on high when it quit. It will not even work on defrost. I can feel heat(barely) coming out of vents. When I spin the temp wheel I can it here it clicking. I have checked the fuse for the blower motor. I read there is a strip fuse to check? Where is it? I read a thread where the poster was told to apply 12 volts to the blower motor. But not sure how to do that. Basically I want to check all the easy stuff before digging under the dash for the blower. Any help would be greatly appreciated. Thank-you! It's gettin cold out there!

[jt20]

Replace the fuse on principle unless you want to get digging right away.

Next, I would use an ammeter to determine the change in current across the fuse when the blower switch is changed.

Then I would start digging and apply the voltage directly to the blower (how?... you need a battery with some leads on it).

last, I would pull the blower and check the contacts, they should be replaceable. Search for write-ups done by other members.

[toledodiesel]

I have an 87 300sdl and when i first bought it the blower motor quit working. I had to pull the motor and squirrel cage out and the bearing was starting to seize up. I applied some oil to both bearings for several days and it has been working fine for 3 years.

Mike

[ShaggyDiesel]

I've been having problems with mine as well, check your fuses first (IIRC #8 16 amp (red)), the CCU may have fractures in the solder contacts, also the heater control unit may have crapped out.

[vstech]

my SD has the blower fuse at #11 and it's a blue 25 my fuse kept melting so I did the MB upgrade to an external fuse. if your fuse is melting you need blower bearings.

[Scott98]

Originally Posted by jt20

Replace the fuse on principle unless you want to get digging right away.

+1. These fuses are exposed to the elements and oxidize over 20+ years. They will cease working even though they aren't blown. Replace them all with new ones. It isn't expensive. Do the simple stuff first before potentially wasting time on more difficult problem solving measures.

Scott

[Jeremy5848]

And use copper fuses, not aluminum.

Mercedes blowers tend to operate right at the limit of their fuse as they come from the factory. As the blower ages, the bushings wear and get contaminated with dirt. This puts more load on the motor and causes it to slow and draw even more current.