Cadillac 1963 heater control

[cadillac 1963 conv]

Hi,
My name is Mauritz and I live in Sweden.

I have a problem whit the 3-way vacuum rotary switch in the heater control.
It has 3 nozzels, 1= out, 2 = in, 3= out. I don't understand the funktion of the switch. I have tested it in this way. I Connect a vacuumpump to nozzle 2, conect a hose t 1 and 3. The heater in 0 position. I pump up the vacuum to 15-20 hg and then mowe the heater arm a little bit to right and the vauum disapers and can't be pumped up again. Is that the right function?  or is the rotary switch broken?
I would be grateful if someone cuold help me...

[TCheo]

Typically the engine would be producing a constant vacuum while it is running. You can't really reproduce this with a hand pump. Once the control unit vents the tube, you will lose vacuum pressure. I'm not sure about the heater system on a 63, but it might be worth buying a factory manual that has a vacuum routing diagram. I had some success chasing a vacuum leak by first starting at the diaphragms directly. Introduce vacuum there and make sure they open, then move to the other end of the hose and make sure that you retain vacuum. The rotary vacuum switch will vent the hose to close the corresponding doors when you change the setting, so a vacuum pump may not work. Once you make sure none of the hoses are leaking and your diaphragms are functional, you may need to test the system with the engine running.

[cadillac 1963 conv]

Thanks for your reply,

I have a shop manual with the diagram of the vacuum system.

I can see your point - test with the engine running, I will do that.
But first I have to mount everything back. i have dismantled everything seeking for faliure. It would take some time......