The heat/ac selection of vent (blows in the chest/face area) quick working. Started tearing into the system; removed the vacuum actuator which cycles when you select the above functions..............it had engine oil in it which apparently rotted a hole in the rubber bellow thing making it t/u (totally unusable Did a little more tearing down and it looks like the check valve on the vacuum pump failed.....spring holding the ball bearing thing was shot. Looks like a bunch of work to get this stuff working. What else do I need to replace to ensure future failures don't pop up? My chariot let me down....just a bit.

 

There was actually a recall on those trucks, way back, to install that check valve, to prevent oil from migrating into the vacuum system. The recall may have to be tracked down to find the part number for that valve.

I would rinse out the vacuum hoses with brake cleaner, and blow them dry with compressed air, then replace the failed actuator. Hopefully that's the end of your trouble.

The recall also recommended orienting the main vacuum hose so the nipple for the heater branch is pointing up. Good idea to make sure that is done.

 

Think the recall was only for '94-'95.
http://dodgeram.info/tsb/recalls/720.htm

In the recall the dealer was supposed to replace any components fouled with oil. Can get very pricey, the speed control servo, the heater and air conditioning vacuum controls, and on 4wd vehicles, the front axle and transfer case vacuum controls.

I would definitely try cleaning things first.

 

Oops! Remembered the recall, but apparently not the model year. Thanks Infidel for the correction.