On my 79 MX-32 Cressida I have found the vacuum actuated blend door on the heating system isn't functioning correctly. I cannot get any heat out of the system, and I found a vacuum actuated servo on the drivers side under the dash that when moved by hand makes heat come from the vents, but it doesn't move when operating the dash controls. There is what looks like a vacuum reservoir along the passengers side frame rail in the engine bay that has one line from it through the firewall, but the other barb on it goes nowhere. My guess is that has to go to a vacuum source that is no longer there due to the PO removing the stock carb, emissions equipment, and such. Can someone verify that this is the case? If I am right could I just run a vacuum line from the carb base somewhere for a source of vacuum to make this operate, or does it need to go through some sort of vacuum switch of some sort?
The Chiltons manual I have doesn't show any vacuum routing other than emissions stuff.