Leaderboard

You should feel a large increase in air flow in the upper vents when you close the lower vents. Had a similar problem on my Ford Explorer which may not be related to your problem. The problem was where the solenoid push rod attached to the seal plate for the floor vent the plastic was broken. Was able to fix with a small cable tie to connect the solenoid push rod to the seal plate. This saved a lot of $ and work as I was able to do the repair without taking the dash apart and it lasted at least 10 years until the car was later sold.