I have tried letting the car idle to raise the temperature to a high enough temp. to bring the fan on. It won't ever get hot enough. However it goes to 100C or a little better and you can stop the car and the fan is not running. Is there an easy way to check and see if the fan is OK. I looked at the fuses and found no bad ones. It is a 300SDL.

The switch for the diesel engines won't allow fan to run until 110C, unless the A/C is on. Could swap to a GAS engine switch that switches at 100C(red color) or 105C(green).

Thanks a bunch! I will do a couple of other things first, change thermostat for one and try that once it warms up if I am still running hot.