No heat from the vents on a 93' Grand Voyager!?

[Bratfalken]

I have discovered that the heatervalve does not move on our Plymouth Grand Voyager 1993 3,3L. There seems to be a vacuumhose that's supposed to operate a regulator on the hose from the coolingsystem, but no matter how I set the heat from inside, there's no suction in the hose. Right in front of the regulator is a connection from the intakemanifold, that thing seems to work, and as I can see in my Haynes there's a wire/ from the settingknob on the panel, but how and where is the switch from mecanics to vacuum, wich panel should I remove and what might I find there? It's very cold outside and I would like to get this to work fast and with less problem as you might understand! Please help me!