Chevrolet: Poor airflow through heat/ac system, ac evaporator, audible difference

Question
I have a 1992 Lumina Euro 2Dr Coupe with the 3.1 liter V6. I get very little air flow through the vents/defrost/heat. The air gets plenty hot or cold, but very weak flow. All of the speeds appear to work, but very little audible difference until on high, and the sound is muffled like something is plugged. It has steadily gotten worse over the last several months and now is almost useless. Any ideas?

Answer
Hi Jay, on your car the flaps that control the direction of the air flow are vacuum operated. Check to see if they are all working. Remove the fan motor to see if the fan has any damage(its located under the dash to the far right) and make sure it runs freely. Check where it takes in the outside air for blockages. And maybe the heater core/ac evaporator itself is plugged with dirt, remove it and blow it out with a air hose. I hope this helps you, if you need more info let me know. Regards, Keith.