No heater controls

This van had a front heater core leaking. One awful job that is. Now I find there are no controls for defrost or heat. Fan runs fine at all speeds and there is heat coming out of both defrost and lower vents but can't change settings from the heater control panel. From what I make of it, it appears there are electically operated vac control relays and vac motors. I'm wondering if it's lack of vacuum. If I'm right there must be a vacuum line and source.

Anyone provide hints or a vacumm diagram?

thanks

Found the problem. While the vehicle was running I moved the wires which attach to the vacuum control relays (located under the glove box). I noticed a change in air flow and sound. Closer expamination revealed a number of broken solder joints on the connector on the printed circuit board. Not really sure how this came about. It could have been some of my own doing while struggling with heater cores. Anyway a five minute re-solder job and we're back in business.