... but I've been surprised what "normal" is before.
I have a '97 Ram Van B2500, standard AC (front only). Under idle or cruising conditions, all is fine & ac comes through the dashboard fairly strong (might need recharge).
Under acceleration or hillclimbing load, the ac comes through the lower (heater?) vents. When I back off on the throttle, the ac again comes through the dashboard. When the ac's coming through the lower vents, nothing comes out the dashboard.
So, is this normal behavior? If not, what would cause it? I know that the heater/ac are a single black-box unit, but my Haynes manual doesn't describe it very well.