Let's try this again, shall we? Here is a copy of my prior response - I will add clarifications in bold:

There is a main vacuum switch located next to all the other vacuum switches that controls the on-off functioning of the entire system. It is supplied with vacuum from the intake manifold via a thermoswitch located on the bottom of the servo (or is it the servo bracket – memory’s going…)The line is black to one of the ports on the thermoswitch, and is of a larger diameter than the other CC vacuum lines. . If the same previously stated main switch does not receive vacuum (from the manifold - via the aformentioned thermoswitch) , the system blower will not turn on. This is likely to be your problem. However, whenever you select the defrost button, the blower & AC compressor will be supplied voltage directly, without the need for vacuum to operate ANY of the vacuum switches that *normally* control those functions. OR you could have a large enough vacuum leak from elsewhere in the system from a leaking diaphragm, switch, or connector which will not allow enough vacuum to develop to operate some/any of the vacuum switches. Whip out the vacuum pump and test every diaphragm in the system. If they are all good, check the vacuum switches directly – current should flow (continuity) when vacuum is applied.. The fact that some of your vents don't open is yet another symptom of no vacuum to the vacuum switches - certain vents are controlled via one or more of those vacuum switches - I'm working from memory here, so I can't be more specific without risk of disemenating erroneous information

SO... Did you check the main vacuum source thermoswitch, all the diapragms, & the vacuum switches? When you find the actual problem, (which WILL be the cause of) a lack of vacuum within the system, let me know if you want to unload that new servo of yours - I could use one for one of my 107s.

RTH