Your blend door is not closing correctly... either out of adjustment or the flap/door is missing insulation.
Look under the dash (from the passenger side) while moving the heater dial from cold to hot. Look for a
lever at the bottom of the heater box housing... the lever should be moving back and forth as you move the
dial back and forth.
Like in this video: (different year model vehicle but similar operation.
If the lever seems to move well, you will need to check the blend doors for missing foam: (different year model but similar)
When the blend doors get old, the foam falls off and there is no more control over where the air goes.
Thursday, December 13th, 2012 AT 7:25 PM