99 E300D is overheating. It went to the red line so I turned the climate control to hi heat and the temp dropped to 95C. Shut heat off and the temp climbs after a few minutes. I am able to control the temp by using the climate control on hi heat.

The aux fan is working, the fluid level is good, and I can see the shaft for the water pump spinning.

So I changed the thermostat. Still no good. Same exact problem.

What else is in the system? Bad radiator?

Thanks,

Mike