I have 91 lumina and the air flow coming from any of the vents in any of the climate function modes seems very weak. I would compare it to a low or medium speed on any other vehicle I've ever owned or worked on. Every function works and the air teperatrure coming out is very cold in the summer and hot in the winter, but there is such low air flow that it takes a long time to warm or cool down the inside of the car. On some hot days, it never seems to be quite enough air flow to cool down the car completely, so it is necessary to use max AC on full blower the whole time. I have disasssembled/cleaned the front cowl intake all the way to directly view the blower and it is running properly. I have just disassembled the under dash and verified all the air doors are opening/closing properly. All the fan speeds work and the blower sounds like its moving alot of air. I have not removed all the duct work, but see no obstructions from what I have removed- which is considerabe.
Is this typical for this model and year. I have noticed a few other posting for this condition, but I am way past trying the basic replies suggested. Any ideas on defects or even upgrades to the blower motor or wheel fan design- to move more air? It seems the air tubes going to the dash vents are unusally small in size- perhaps to increase the air speed as it moves through them- maybe this overly restricts the volume needed for the car interior?