98 Eldo AC !&#@ sends Cold air to defroster !&$#%

My 98 Eldo keeps sending the AC Blower air flow out through the Defroster port. It switches to and from the normal AC dash registers to the Defroster vent/port about every five minutes or so, though it seems to be completly random. It does this whether engine is setting at idle or excelerating or braking. Tried to correlate it with some change in Vacum pressure but am unable to associate when it switches to any change in rpm.

Can some tell me where the door/gate is located that routes the air flow and what controls it? IE vacum, electrical, computer... I'm in Texas and keep the air set on 60 degrees and AUTO.

Any help would be greeeeaaaaaatly appreciated.

Tks - Jay [email protected]