1996 E320 A/C Heat Fan
 

The blower fan in my 1996 E320 has been working sporadically for a few months now. Sometimes it comes on immediately after I turn the car on. Other times, it will not run for several days. There seem to be no pattern to this. No matter what I set the fan or temperature to, it seems to have a mind of its own. It's still pretty hot here in Florida and I really would like to have the AC blowing. Any help would be appreciated.

Probably the blower fan itself, it's a fairly common failure.

1996 E320 A/C Heat Blower Fan
 

Is replacement of this fan relatively easy to do?

Yes it's pretty easy, it's under the glovebox area (lay on your back in front of the passenger seat, under the dash). You could then just jump power to the fan to see if it works.
Only problem is you might have to buy an updated fan which means you have to buy a regulator to go with the fan.
Gilly

Might get to it and see if you can replace the brushes or grease the bearings.