I am not getting any power to the vacuum valve on pod #4 on my 81 SD. This valve is the one that controls the main air flap in the dash. It functions perfectly when I apply vacuum manually and holds vacuum well but due to the pack of power it does not open.
anyone have an idea why this one would not work while all the rest do?
This is a rebuilt controller so it is functioning correctly as verified in my other car.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

The center flap actuator is an oddball in the group. It gets constant power and switched ground. The signal for the center flap comes through the ACC push-button unit from the temp control unit so that's something else to consider.

Sixto
95 S420
87 300SDL

I'll pull the temp sensor and chek it out too. I am now getting heat and then it will slowly go back to cool air. Then a blast of heat then back to cool air.
I just duct taped the foam hose back together in there but should have pulled the sensor and checked it.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

We might be talking of different things. The temp sensor is the device in the dash or by the rear view mirror. It's not the same thing as the temp control unit which is the brain that determines the function of the monovalve and AC compressor in total ventilation, normal and economy modes (3 middle buttons). Later 126s have this function done by an integrated push-button unit. Early 126s have the temp control unit in the right kick panel IIRC.

Sixto
95 S420
87 300SDL