I'm back. This time it's the blower motor. I was driving home and it just stopped working. Everything else appears to be working fine.

I pulled the glove box. I checked for power at the connector for the blower. I had 12 volts on the positive wire, but I had varying voltages on the negative depending on where I set the blower speed on the AC unit. Behavior I didn't anticipate.

I hooked to motor straight to the battery. Works. I replugged the connector, no work. I then used a wire and stuck in the connector to ground the negative side. Blower comes on.

I'm looking around the internet for what might be at fault and came across the blower resistor. I figured that'd be worth looking at. I located it and noticed the solid brown wire shielding was burnt. I unplugged the connector and it was burnt. Not melted but blackened.

I checked the resistance on the resistor at the two brown wire connectors. It was open. Being that the brown/green comes from the blower motor, I'd expect this to have some value.

Oddly, if I measure voltage on the solid brown wire, I get 3 volts. I get 10 volts at the third, non-brown wire.

Soooooo, my first thought is the blower motor resistor is bunk. Open circuit seems broken. However, I am somewhat confused by the 3 volts appearing on the brown wire. Where does this brown wire go? Does it go to a relay? Does the system apply a varying voltage to the ground side of the motor to control its speed? Seems an odd way to do it, but why else would 3 volts be there on the ground wire? A bad relay? Where might such a relay be located?

If this is confusing, I'll try to clarify any questions.

Thanks

 

No ideas? I guess I'll order a resistor, as I'm fairly confident it is bad. Hopefully that will be all that is wrong.

 

My goodness. These things are not cheap. Any recommendations on where to get one less pricey?

 

I had a post on this a few months ago. I have the solar powered sunroof, can't say for sure, but I think that has a negative effect on on those, as the blower would be running for hours while in the sun, so the resistor would get hot?
Both times they went out there was a burnt area. So sounds like that is the problem.

 

Thanks Euge82. I don't think I have the solar powered roof. Looks like a regular glass roof to me. Granted, I'm not sure how to tell, but I would guess you'd see some form of solar panel in there.

That resistor has certainly gotten hot. I've found some off brands for around $80. I guess I'll get one of those.

 

I've been having similar issues. I replaced my blower resistor a couple years ago (part cost me $160). I noticed the same overheating problem with one of the connecting wires. Some of the wire casing even melted away. The plastic around the connection pin on the resistor looked to be melted some. My guess is that the heat eventually fries the inside of the resistor. All I could find on possible causes of the wire getting hot was connection issues. They say to clean the connection point. I think there has to be another cause, some other faulty component. Anyway, I see no point in spending hundreds of dollars on resistors is they're just getting fried. I found some on EBay for under $50. They are technically used, but they are original Audi parts, not after market. Definitely a better way to go, at least until this wire overheating issue is resolved.

 

you are correct the resistor has overheated, pick one up on ebay for around $50.00.

 

After replacing a portion of the wire last year, once again my blower has stopped. When I took off the glove box I noticed that the heat in the bad wire has totally melted the wire nut I used to add on a new piece of wire. I also have had no luck finding the path of this thicker brown wire from the blower motor resistor. I don't believe it always gets hot and stays hot. It seems more like something causes it to get very hot at certain moments. That's why it survives at least a year. There are just too many wires banded together to really be able to track the path of one. If anyone has had any more success with solving this issue, please share.

 

Change the cabin filter. If it's clogged you will draw too many amps and burn the wiring. It's either that or the motor bearing is going bad. Easy to just pull the filter and feel the wires while the blower is running. Hot is bad, lol.