Toyota Repair: heater and air cond not effective, control knobs, toyota celica

Question
QUESTION: I have a 2002 Toyota Celica GTS, my problem is that very little actual moving air comes out of the vents.  This renders the heater and air conditioner almost completely ineffective.  I have had two mechanics look at the problem, both have assured me that the blower is working fine, but they can't tell me why the heat and air cond. don't want to work properly.  This problem is through all of the settings, whether defrost, floor, or any of the other vents.  The fan/blower turns on and I can hear it run, and you can hear it get louder when you turn the fan up to high.  The last mechanic said he thought it might be a blend door inside the plastic housing under the dash....I would greatly appreciate any advice you may wish to share on the subject.  Thank you and have a great day.

ANSWER: Does it have auto climate control with pushbuttons or manual with knobs and levers?

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QUESTION: the controls are manual and seem to function normally.

Answer
It's possible that one of the control cables has come of the blend door, remove the glove box and look for a control cable that connects to a blend door make sure it is still attached to the operating lever on the right, also check underneath the left side of the heater control unit, make sure all the cables are moving all the operating levers when moving the dash control knobs.