Chevrolet: Heating & cooling fan, chevy cavalier, shadetree mechanic

Question
I have a 1993 Chevy Cavalier that is not blowing much heat or cooling from the dash vents or below at your feet. The heating & cooling is fine, the defrost seems to blow OK, but the dash & floor vents don't blow well. It was checked at a garage about a year ago, but they didn't find anything wrong. Any thoughts?

Answer
Does it blow low even on max? How does it blow on the windshield? If its low, than its the blower motor. If not, keep reading...

I would guess its the diaphram thats bad or the door jamb is dirty.

When you switch it to dash or feet, a diaphram inflates or deflates which opens or closes a door blocking off air to other vents and opening up the dash and feet ones.

The diaphram and door is usually located up behind the glove box. Its pretty hard to access and usually requires you to disassemble half the dash.

Not an easy job for a shadetree mechanic.