When I'm driving with the blower on, the air flow sometimes redirects down to the floor vents. If I let off the gas, it comes back through the dash vents. I assume this is a sign of a loss of vacuum to the air duct directors (or whatever they're called). Do you think I'm on the right track?

 

You sure it's redirecting to the floor and not the defroster vents? Usually a loss of vacuum directs airflow to the defrosters. Besides a vacuum leak, this can also be caused by the in-line check valve (one-way valve) leaking. This check valve is located in the vacuum hose that leads to the vacuum reservoir for the heating system.

 

On my '93 B150 one of my vacuum tubes in the engine compartment near the right firewall (a black one if memory serves) was rubbing against the end of a metal hose clamp near the heater control valve. The rubbing was enough to wear a small slit in the hose where vacuum was being lost. End result was same as you describe, dash vent air being redirected to floor. I replaced the bad tube and everything returned to normal.

 

how do i check for vacuum leaks? wahaca69@yahoo.com

 

Under the hood? Take an unlit propane torch and direct it to the suspected area. If idle speed increases sharply........you've found it!

Just be careful.......................

 

well i give it a try? thank lilredex