Yet another blower problem. The car was parked for 2 weeks and now the blower won't work. I removed the blower motor, cleaned lubed and tested, it works fine. I am not getting power to the leads for the motor. I tested the fuses, they are fine. I jiggled the key iin the ignition a bit, no change. All other lights and accesories work fine. The motor will not work at all on any setting. It worked fine before ( a little squeaky). Next step? Regulator under the blower mount? Any ideas???

1993 E300D 2.5t
150,000

If you still have the blower motor accessible, it's pretty easy to see if it's the regulator. Just hook a wire onto the ground wire (blue one) and ground it out. If it works, then the regulator is bad, as the regulator only controls the ground. When I had my blower out, I put a wire on the ground and fished it out through the firewall, so now if I have problems, I can test the regulator without taking everything apart.

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87 300D - Running on Veggie oil; 260,000 plus miles; Original #14 head

Tested blower as suggested by grounding wire. No response, rested leads with a line tester, no juice. Removed and cleaned fuses and contacts, no change. On to the climate control? Any suggestions out there for REPAIRING the climate control?

Was there axial play in the blower motor? Did you test it in the same orientation as it's installed?

Sixto
... stay tuned

I tested the motor by holding it in my hand and hooking leads to a spare battery, also did leads to the battery in the car. It spun great both times, gave off a lot of air. I used some contact cleaner on the brushes and some penetrating lithium grease for the bearings, it does spin more freely now.

I am not getting power from the motor leads in the car, I am also not getting power form a three wire plug at the top left of the fuse box (drivers side). It is a flat plug with a black, red and yellow wire. My wiring diagram does not clarify this connector, but it seems connected to the blower motor wire group.

The climate control circuit board did not have any obvious "burn" marks, or signs of a short.

Sorry, direct answer here, no it was not in the normal orientation, and I did not detect any axial play.

The blower power is unconventional (to me). There is constant +12V with ACC system on and varied low voltage to set blower speed. One blower wire should get +12V regardless of blower speed so if you don't see that then recheck the fuses. Scratch that - replace the fuses. Those fuses can look okay but not conduct electricity. IIRC that model has an external fusebox for the blower fuses. Or maybe handled as a silent recall. 2 15 amp fuses in parallel or something like that.

Sixto
... stay tuned

did you check the metal strip fuse (not in the fuse box), the one on the drivers side wheel well next to the abs box (little match box size box) relace that .95 fuse, they come in 30, 50 and 80 amp sizes, check for voltage accross it.

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1993 Mercedes Benz 300D 2.5 205K (ex wife's)
1984 Mercedes Benz 300SD 320K (SOLD)
2004 Mercedes Benz C240 75K
1995 GMC Sierra 2WD 5.7L 188K
1983 Mercedes Benz 300SD 239K (SOLD)
1987 BMW 325i 220K (SOLD FOR SALVAGE)

609 Certification

Ok, I'll replace the fuses and check the "matchbox" one too. i'll report back in the afternoon. local MB mech is pretty sure its the ccontrol, theory is the car sat, blower froze (it rained like hell those 2 weeks), and shorted the ccontrol when the car was started.

I was always under the impression that the positive wire for the blower came straight from the battery and always has juice running to it, I didn't think it came from the controller, but I could be wrong. I wish I had a wiring diagram for the car, because I don't want to give bad advice. But if you aren't getting any juice to the positive terminal, then likely the blower and regulator are fine. It does sound like a bad fuse.

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87 300D - Running on Veggie oil; 260,000 plus miles; Original #14 head

Ok, I went from being 75% sure it was the clim control to thouroughly confused again. i did not replace the fuses yet, but I have a 12V tester that lights up at both ends of the fuses-I also cleaned the fuses and connections. Here is where it threw me, I got the tester to light up off the red blower wire. I plugged in the motor-nothing. Put the tester on the red blower wire again-no juice. Turned the car off then on again-tester said power in the red blower wire, hooked it up, same as before, no power to the red wire. Traced the regulator wire to a connection behind and to the left of the fuse box. Similar juice no juice symptoms (the black yellow red the prong thing). Mercedes mech thinks clim control, but that does not explain lack of power to red blower wire. all vent doors and ac functions work great too-just the fan will not run. Any more ideas? Ignition maybe?

What voltage do get at the other blower wire?

Sixto
... stay tuned

I found the "Matchbox" fuse, not shown in manual or on my wiring diagram or my Haynes manual. The fuse is broken. I checked a couple other things, the climate control illuminates with the headlights on, AC works great and seems temp sensative even without the blower. I cant make out the number on the flat fuse, what should I replace it with and is it indeed for the blower?

I believe it's 30 amps. You could start with a 15 amp fuse and work your way up. No more than 30 for sure.

Sixto
... stay tuned

Here are pics of the flat fuse.

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