Anyone have the schematic for this or possibly blower motor is broke. It never worked since I had it for short time. Any other things to check?

My 78 W200 did the same thing.....until I wiggled the blower motor fuse. Came right on....

Run a jumper wire from the battery to the fan and see if it runs. If it runs then check the blower motor resister on the heater housing for power in and out.

Are you talking about the fuse in the glove box on top of dash or is there another fuse down on the blower motor under the dash?

There a resister in the top of the heater box that burns out too
If you find it burnt change your blower motor

Fuse in the glove box.