As Gilly said, the blower motor is under the windshield wiper assembly annd motor, and apears to be a job that's not too difficult, and may take 2-3 hours.
I've experimented a little with disassembly of the wiper unit to look at the blower motor, and it's not impossible for a DIY'er to do it.
To take out the wiper motor, you first open the wiper arm cover, loosen the hexagon socket screw, and remove the wiper arm. You then unscrew the 4 hexagon nuts, take off the retaining clip, unplug the electrical connection, then take out the wiper system unit. Then, you unscrew the hexagon nut of the wiper motor shaft, take off the crank arm with the attached linkage, and then unscrew the wiper motor.
Once the wiper motor is out, you can see the cover for the blower motor. The cover appears to be held in by clips. You can also see the outside air temperature sensor that you'd have to unplug.
Once the cover is off, the blower motor comes out. I didn't pull my motor out, but I'm guessing the motor justs rests in there and can be pulled out.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".