Was driving with a friend today, turned the AC on to cool the cabin down, then we smelled a horrible burning rubber smell. Because I had company, I just turned it off to worry with it later. I've learned since then that the fan will not even turn on, whether it's on 1 or 5 speed. Any ideas?

 

Most likely the fan control/resistor board that is attached to the bottom of the fan.

see https://www.crossfireforum.org/forum...where-get.html

 

Replaced the blower resistor today--still no fan. Also checked fuse #37 and it is still good. What could it be?

 

The blower motor, or the control panel assembly.
I'd try the blower motor first, it's cheaper.

 

I have the same problem. Still trying to source the problem.

Mercedes,,,best engineered cars in the world, made with the cheapest parts.

 

Pulled the blower motor yesterday. To test it, I hooked it up to a 12V power source, which made it blow full speed; however, there was a horrible electrical burning smell while it was running. Any ideas?

 

Shorted -partially windings. Motor will overheat if current is too high. Woody

 

So, then, what would you advise to replace?

 

The fan.

It should run fine when hooked to 12v without smelling or smoking.