A/C Intermittant Fan
 

On my 1991 300E, the A/C, Heat, vents, etc. all work - what doesn't is the fan in any speed (Auto, High, Low) on a consistant basis. I've gone full days without the fan working. If I have the temperature set so that the A/C should be on I do feel cold air from the vents just without and fan blowing it out. Other days after driving for differant amounts of time the fan will suddenly start to work and I can then change it to any of the optional speeds. Any hints about where to look for a fix would be greatly appreciated. Gets fairly sticky this time of year in North Carolina and it's only going to get worse.

The electrical switch at the back of the ignition may be worn. Try playing with the key by turning it a little with the car running. If the blower comes on replace the switch. If that doesn't work it may be the blower motor regulator.

Good luck.

My car did the same thing. I can safely say (99.9%) that it is your ignition switch.

You may have a problem with worn out brushes in your blower. I have had mine apart 3 times for the same sort of funky intermittent operation. The regulator was replaced once, which did not cure the problem. If it comes on suddenly when you slam or close a door and you've got it on high or auto A/C, then you've got intermittent contact. I'd take a hard look at the motor itself. It's not likely to get any better with time.

the manual seems to describe a procedure that is very DYI. This looks like most of the cost would be for labor. Is the regulator seperate from the blower itself?

Yes it is.