Blower motor doesn't work, blows fuse - PeachParts Mercedes-Benz Forum

dsvw · #1 08-04-2021, 01:33 AM

Hi,

I appreciate all of the guidance I have received as I sort out my newly acquired 1986 2.5L automatic 190D

I am still waiting on my service manual.

My blower motor does not work. When I turn on the blower motor from the switch in the cabin, it immediately blows the fuse.

If the motor was non-functional, or burned out, why would that happen?
Wouldn't it just not come on?
Is it possible that the motor works but is somehow locked up?

Thanks.

rrgrassi · #2 08-04-2021, 06:39 AM

Drawing way too many amps. A dead motor can cause a direct short, thus blowing the fuse.

jsb357 · #3 08-04-2021, 08:11 AM

Unless the motor is shorted even if the blower is locked up,
there should be a brief pause before the fuse pops.

i used a small motorcycle battery to power the blower
to make sure it was not locked up.

On my 560 SEC the smog pump wiring was on the same circuit and the
wire in the engine bay was chaffed and directly shorted to ground.

See what else is on the same circuit on your 190 and start digging.

psaboic · #4 08-04-2021, 09:54 AM

Agree with jsb357. Try to test the motor with a spare battery or other high amp 12V power source. It is either the blower motor or something else on the circuit is causing the fuse to blow. The thing to remember is if the fuse only blows when the blower switch is turned on but is ok at any other time, then the cause has to be anything downstream of the switch that is energized ONLY when the switch is turned on and supplying power. Most likely the blower motor itself (and a test with a separate power source as mentioned above should confirm that) or a wire chafed and shorted to ground.

psaboic · #5 08-04-2021, 09:56 AM

Just a thought, can you electrically disconnect the blower motor easily? If so, disconnect it and try the blower switch. If the fuse does not blow, the motor is your cause. If the fuse does blow, look for bad wiring or something else shorted to ground or pulling too much amperage.

vwnate1 · #6 08-04-2021, 07:07 PM

Carefully remove the knee panel under neath the passenger side dashboard, look up from the foot well and find the blower motor ~ it has a molded hard black plastic plug ~ gently pull it free by the PLUG not the wire and see if the fuse still blows .

If not, the motor is bad or possibly locked up due to leaves accumulated or a mouse nest....

There are several 7MM hew head screws and one #2 Phillips head screw then it drops down for easy cleaning / service or replacement .

Once it's down stick you hands up in the open hole and reach to the left, I've found all manner of crap in there (the plenum) and a tiny bit of crud will screw it up .

FWIW, I'm using a URO brand replacement and so far it's working better than any serviced / repaired originals did after 30+ years .

dsvw · #7 08-04-2021, 08:13 PM

Can you get to the blower motor from underneath and inside the cabin in the 190D?

I thought you had to come in from the engine compartment after removing the windshield wiper motor....

rrgrassi · #8 08-04-2021, 08:48 PM

Can you put your car info in your signature?

On my 91 w124, you access the blower by removing the mono wiper system. The w124's are like that. I do not know about the w201.

vwnate1 · #9 08-05-2021, 12:50 AM

Sorry, I was thinking about W123 & W126's...

I'm sure there's a plug you can reach and disconnect for testing...

Youtube should have several videos, be sure to watch many as some won't have the proper sequence , BT, DT dammit .

I hope it's not like an old Volvo brick heater, that one you have to take the car off the heater, not the other way 'round

.

Usaguy · #10 08-05-2021, 08:44 AM

Quote:

Originally Posted by dsvw

Hi,

I appreciate all of the guidance I have received as I sort out my newly acquired 1986 2.5L automatic 190D

I am still waiting on my service manual.

My blower motor does not work. When I turn on the blower motor from the switch in the cabin, it immediately blows the fuse.

If the motor was non-functional, or burned out, why would that happen?
Wouldn't it just not come on?
Is it possible that the motor works but is somehow locked up?

Thanks.

To check for a short to ground somewhere you can test the blower resistor and the wire going to the motor.

Apply one end to a terminal on the resistor and one to the ground and see if there's continuity. Do that with every terminal except terminal 5 on plug x1(ground). The plug at the resistor goes to the motor as well so this way you will check the motor wires too.

Sugar Bear · #11 08-05-2021, 09:34 AM

Can you post a picture of the blown fuse focused on the burned/broken spot?

dsvw · #12 08-06-2021, 11:19 PM

I replaced the original blower motor today. The bearing were shot, I think that is probably why the fuse was blowing. Thanks for the help.

rrgrassi · #13 08-07-2021, 03:11 AM

Quote:

Originally Posted by dsvw

I replaced the original blower motor today. The bearing were shot, I think that is probably why the fuse was blowing. Thanks for the help.

So, how did you get to the blower motor?

dsvw · #14 08-07-2021, 07:32 AM

Remove the plastic drain/cowl that runs under the windshield. Remove the windshield wiper assembly along with the wiper motor.....that is one piece. If I remember correctly that is something like 3 nuts up below the cowl area, the bolts that hold the motor assembly in place and a screw going through a white plastic piece right below the center of the actual wiper. Remove the electrical connection to the wiper motor. the You will see a black plastic box that the blower motor sits in. Undo the clips on the two sides and top. Remove the metal band that snaps the motor in place and gently wiggle it out. Be careful not to drop any of the nuts and bolts that you remove to get the wiper assembly/motor out. You will never find them again. While you have everything out, now is a good time to get in there and gently clean all of the crud off of the a/c component.

vwnate1 · #15 08-08-2021, 11:01 PM

Thnak you for the follow up ! .