1989 Mercedes Benz 350sdl Climate Control Fan Motor

The fan for the Climate Control is intermittant as to when it will run. Some mornings when I start the car, the fan will start when the car starts. Other times it will not start when the car starts but will start automatically as I am riding along. Now I am making dirves with the car without the fan ever coming on.
When this first started, it seem that turning the motor off, and restarting would allow the fan to start. That solution has gone away.

If the fan does not start automaticall, it will not start by selecting the manual button either