99 S10 Blazer just blows air out of dash vents and defrost.

[rontomed]

My 1999 S10 Blazer LT 4.3L 2WD with Computerized Climate Control (can run as Auto or Manual climate settings) would not switch air flow to the floor. I had defrost and top-vent all of the time no matter what position the switch is in, but not to the floor. Under the hood I have replaced 2 short 5/32" vacuum hoses that connects to a T junction (the other ends where connected by feeling, I could not see them) and 1 long 7/32" vacuum hose that runs from the same T junction to under the throttle body. They where all rotted. Air through the T junction flows in one direction as I think it should. Now it works at times. After driving a short distance, all worked well. After an hour of the vehicle setting still with the engine off, it would not change to the lower heater vents. Four miles down the road it started working again. I can not find a plastic vacuum ball. Is it the nipple sticking out of the finder well into the engine compartment or under the Kelsey - Hayes ABS system? How can I gain access to it? Any other possible causes?