One Sided A/c

My 2000 Venture his only putting out cold a/c on the passenger side and the rear, but the drivers side and the middle vents blow warm air. A friend suggested something might have come loose in the venting system so i've torn most everything out to take a look. When I turn the temp knob to hot or cold I can see the Diverter Motor working but not sure if it's actually turning what it is supposed to. It does get hotter when turned to hot but I can't get any cold air thru those vents. Suggestions? I pulled the diverter Motor and manually rotated the knob and it seems to work correctly to give more heat but I still only can get cold air out of rear and passenger sides. This is beginning to sound major repair.

I've just noticed the same symptom with my 1999 venture. Haven't torn it apart yet (beyond just cleaning out the two filters). If I figure it out I'll let
you know; meanwhile, if you do before I do, please let me know as well!!!
Ed