i own a 1995 villager,same problem.there is a ground relay in the back of the front control.take the back off and disconnect the ground wire from it and run it to frame ground.it will save you 440 dollars from buying another control .
if its the same set up as mine then its a 2 switch combo. One switch is located in the rear to control the rear heating and cooling system and one is located in the front so the driver can control it as well. If the front one malfunctions it will cause the rear one not to work at all. I do believe the new switch cost about 50 or so.