'93 190E blower has one speed
 

The heater/AC blower motor doesn't work at all when I first start driving. About 5 (or so) minutes into a drive it starts blowing, but at a very low speed. Changing the setting on the blower speed control does nothing. Turning the system off entirely does nothing (it still blows at the slow rate).

I've swapped both the climate control unit and the blower speed control unit out with units from my parts car (believed to be good). Nothing changed.

I do get heat from the slight breeze it creates (almost exclusively from the defrost vents).


I tried searching the forum for similar posts, but without luck.

I'm looking for ideas of what to check.

Thanks.
Brett

I'd start with the fuse and determine if you've got a good contact there.

Next I'd hit your defrost button and see if you get full speed, if you don't then you could have a blower motor that's about to die.

If it was the resistor, you'd lose the lower speeds and only have high speed.

Do you hear any squeaking sounds?

Thanks Shyne.
I have good contact at the fuse. Hitting the defrost button does not change the fan speed. There are no squeaks or any other odd noises.

So it looks like I'll be pulling the blower motor. I'm hoping that the repair will be limited to brush replacement (assuming I can find brushes for it).
Brett

I think you'd be better off just buying a new motor, which isn't too expensive, and swapping over your original fan blades onto it. If you're going to go through the trouble of getting to the blower motor, you'll probably want to put in new components so you don't have to go back. I'd consider a new resistor as well.

I can't find it now, but I remember a guy on the 190 revolution board taking pictures of the process of replacing his. From what I can recall, the pictures and write-up were quite detailed. Maybe you'll have better luck searching for the thread than I had.

I wish you luck.

-Mike

Hi Mike.

I pulled the motor off of my parts car yesterday (to check it and to see how involved pulling the motor is. (It was pretty easy with the parts car, as the hood is off, and the engine is out.)

The brushes are pretty worn on it, and it looks like they were not designed to be replaceable (not easily anyway). So I'll likely be following your advice and getting a new motor.

The plastic fan blades (squirrel-cage type) look to be pressed on. Is there a trick to getting these off of the old motor shaft without breaking them?

Brett

Update -- I need diagnostic advice
 

I pulled the motor housing open yesterday. I turned on power to the blower (key in run position, resistor/switch on high, and defrost button pushed). A multimeter showed no power getting to motor.

I then ran power directly from the battery to the motor. The motor worked just as it should.

I have power on both sides of both 30A fuses in the black box located in front of the main fuse box (I don't know which one of those two is for the blower, but both are good).

So my problem is somewhere between the fuse and the motor. I was going to pull out the resistor yesterday, but realized I have no idea how to check it (though I did, when installing a new radio, switch it out with the one from my parts car, and it made no difference).

Where is the likely fault? If it is the resistor/switch, how do I test it?

Is there a relay involved in providing power to the motor?

Any other thoughts/ideas?

Thanks.
Brett