So..I had a cracked cc servo in the 116 and the PO had bypassed the system. I found what appeared to be a good used unit at my local pull a part and pulled it. I took it apart and all the seals seemed to be in good shape.

I did notice however that both on my old unit and the new unit the aux. water pump was seized. I tried hooking it up directly to the battery and nothing happened, plus the impeller seemed stiff to turn.

After I hooked everything up to the new unit, everything worked properly as far as the vent control. Center flaps work, defrost, fan, etc....but I have no heat.

So after this background info I have three basic questions:

1. Is it required for vehicles fitted with the cc servo set-up to have the aux. water pump in working order to push coolant through the valve?

2. I hooked a voltmeter up to the power supply to the water pump and got 12 volts on full heat and defrost....theoretically if I switched the control to auto lo and moved the temp gauge to cool the power supply to the water pump should cut out right? ...because mine does not, it maintains 12 volts.

3. If I have a fried amp I wouldn't be getting vent control..right? Or could that be an issue as far as switching the servo from hot to cold?

I've searched for hours through the numerous posts on this issue, but could not find any answers to my questions above....

Thanks for the help!!

Sam

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1980 300SD 237k
1983 300D 195k (sold)
2003 Chevy Silverado 190k