Symptom: air not blowing through vents. When the blower is at its maximum power (5), I can feel slight movement of air which is strongest above the windshield (defrosting) vent.

Other details:
- Changing the power of the blower: the sound of the fan becomes louder at higher powers (as it always did) but only very slight (if any) difference in airflow is felt (i.e. there is none or almost no airflow).
- air conditioning on/off: no change in air flow/temperature
- air source (external/recycled air) switching: no change in air flow/temp
- air flow dial change (all positions): no change in air flow/temp

What may have caused the problem: I switched the airflow settings (from front to feet only) and back. while having the air conditioning on. I noticed that there is no mechanical effort in the knob like with my previous cars so I presume the flow is being changed by valves controlled by the knob, not moved by it.

I have owned this '92 740TW for 3 monthe and don't remember changing the airflow settings before.

What I noticed: after air flow ceased, I stopped the car and noticed a leak positioned approximately below the center of the dashboard (not under the engine, but further back). The liquid looked like dirty water (not green, not greasy, brownish but almost clear) so I presume that was condensation from the AC running.

Any suggestions of things I can troubleshoot or suggest to my mechanic?
I may take the car to the service tomorrow.

Thank you in advance!

-- Andre