A couple of operational questions - 1) does the servo motor run at all when the system is on A/C? I still have good A/C...

2) Also, if there is an air pocket, would this prevent the servo from operating?

3) Will the heat even operate in this car if ambient temps are in the 90's?

4) Would a bad auxiliary water pump contribute to this problem?

I am just not yet convinced that this rebuilt servo is bad - I tested the old one by connecting a 12v source to the leads on the servo (according to the above link), and the old motor didn't run either. Now it's possible that if the servo doesn't operate while the system is cooling, maybe that old servo is/was bad as well - since I haven't operated the heating system since Feb/Mar.

ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE