Hi All
My 1989 300 se has a problem with heat/defrost at 60-70 mph.The fan blows cold air.Engine temperature was 60 c and would not get any higher.At idle the temp would reach 80 c and i would get heat and defrost.
Today i replaced t/stat with a 87 c stat .Bled system topped off radiator, and the heater drove you out of the car.

Super!! I took the car for a drive engine temp at 87c as we rolled onto the hiway temp started to drop like the A/C was on.The temp got colder as we went along.
Returned to the GUY-RAGE ,played with all different settings on the heater control panel and the heat started to return until it drove you out of the car again.

The aux fan did kick in at idle but am not sure what temp. it kicks in at.

Usually low engine temp no heat means a bad T/stat but this is a Benz and i need your help.

Thanks
Razorman

The first one to solve this gets a 5 pack of the new Gillette Turbo Mach 3s