Originally Posted by KJenkins

I have not been able to get heat in my 1980 300sd with the dreaded evil servo setup. The original servo in the car was not working, severely cracked and plugged up with crud. I recently replaced it with a nice used aluminum unit. The motor in the new servo seems to work because I can hear it running after I shut the car off. I also replaced the amplifier with a rebuilt unit and put in a new auxilliary water pump which is working. When I push the defrost button, the blower comes on but I get no heat. When I push auto lo or auto high, the blower will not come on at all. So i have two questions. Number one, why am I not getting any heat in defrost? Number two, why will the blower not even come on in the auto lo or auto high positions?