W140 A/C Blower Motor - PeachParts Mercedes-Benz Forum

wbrian63 · #1 05-17-2007, 09:30 AM

I used an "amp clamp" around the positive wire to the blower when on high.

The fan is "stiff" - when you manually spin the squirrel cage, it stops abruptly. The bearing used to squeak on low, but a few drops of tranny fluid on the upper bearing got rid of the squeak.

According to the MB manual I read at the dealer the other day the (and I'm working from memory here) "blower is internally protected from short circuits - no external fusing is provided or required" I'm guessing that the regulator provides the protection in case of a short circuit in the motor.

To confirm this, I cracked open AllDataDiy, and navigated the rats-nest of wiring diagrams for the A/C system. Finding the blower motor, the red wire is 12v+ back to terminal block X/10, which is part of circuit 30. This circuit is unfused directly back to the battery. On a 140 sedan, it's on the floorboard, passenger side, beneath the protection plate.

So, in short (no pun intended), there is no fuse for the blower motor.

As for what load is on what item and when, I believe that both the wires for the blower (positive & negative) come from the regulator. If the blower is drawing too many amps (and from the other article linked to in this thread, it definitely is), something's gonna get hot. The odor I'm smelling is definitely the resin used to seal the electronics (I used to work in an industry that used just this type of stuff - I know the smell very well).

Having said that, Tuesday the car set out in the sun for quite a while at the mechanic's shop, so the A/C ran at full-tilt for at least 20 minutes cooling the car down (inside temp at asipirator was 118 when I started the car). I didn't notice the smell this time. It may be that the resin is "gassing off" a bit, and assuming I don't ruin the regulator before the new motor comes in from FastLane, I'm just going to keep using it.

JimF · #2 05-17-2007, 06:42 PM

Quote:

Originally Posted by wbrian63

I used an "amp clamp" around the positive wire to the blower when on high.

If the blower is drawing too many amps (and from the other article linked to in this thread, it definitely is), something's gonna get hot. The odor I'm smelling is definitely the resin used to seal the electronics (I used to work in an industry that used just this type of stuff - I know the smell very well).

Having said that, Tuesday the car set out in the sun for quite a while at the mechanic's shop, so the A/C ran at full-tilt for at least 20 minutes cooling the car down (inside temp at asipirator was 118 when I started the car). I didn't notice the smell this time. It may be that the resin is "gassing off" a bit, and assuming I don't ruin the regulator before the new motor comes in from FastLane, I'm just going to keep using it.

That's the best way to measure the current . . I have a Fluke and it works well but the accuracy of it (and yours) I suspect is +/- 5% or worse. When I measured my it was more like 26 amps or so.

If the blower was on HIGH, there's very little power dissipation in the regulator. So maybe that's why you didn't smell anything.