Is it possible to run defrost without automatic using the switch on the air conditioning?
If so, how can I do this?
As others have stated, it is meant to operate this way. That being said, many of the vehicle specific online forums talk about how to disable it, to allow manual control. Searching, I didn't find a way to do that for your generation Voyager. For the prior generation, it was possible to disassemble and modify the HVAC control.
No one has reported a way to do this on the Chrysler minivan fan club forum, but it has been discussed