Airflow not always to right vents

Hi All,

I’ve been living with this intermittent problem for awhile, it might betting worse. I’ve got a ‘93 RMW, it likes to make a ‘clunk’ sound in the HVAC that I can attribute to the vent selection. Sometimes the air isn’t going to the right place either.

Not unusual to switch off the engine and, as the vacuum goes down, the clunk happens again so it seems like it’s associated with the vent selector “valve” (need a better name). Any thoughts on what I should be looking for before I go randomly digging?

Thanks for the help.

Leaking hose/valve/motor. Use a vacuum test pump, and listen for leaks. You will find the unit under the passenger side knee bolster. It may be a vacuum motor. You can test each hose from the valve, and if they all work properly, it is the valve. One hose goes to the reserve tank on top of the plenum.

Thanks for the insight Fred, knowing what to take a careful look at is always really helpful.
-Leland

Hi all - just to followup, the valve unit (that selects what to do when with the vents) was replaced and all is fine. Though I swear the vents are louder and make more of a clunking sound than they used to.

I'm going to just let that go and allow the car to be 26 years old though.

Maybe that is because you have not heard them for a long time. Give it 30 days, and you will not notice them any more.