Dash only blows thru the defroster

[bill jones]

Before I go under the dash again, does anyone know where the vacuum for the control manifold comes into that little switch under the dash. After our last boon-dock adventure. the dash air only comes out of the defroster vents. I think that is the default position. Help!

[bill jones]

Before I go under the dash again, does anyone know where the vacuum for the control manifold comes into that little switch under the dash. After our last boon-dock adventure. the dash air only comes out of the defroster vents. I think that is the default position. Help!

[RKL2]

Bill....you are correct, it is the default position...you have a breakdown in the vacuum line...
The easiest way to test i9s to go to the vacuum line that connects to the HVAC plastic box which contains the dampers for the vent positions.(Left side under hood.)
I believe there are 2 lines on the box. Start the engine, disconnect the lines one at a time and test for vacuum. If no vacuum, proceed back along the line to the next connection or tee or where it connects to the control panel on the dash....
If you want to go the other way, remove the outgoing line at the vacuum generator (Right side of engine) and test for vacuum..You can proceed along that line then to the control module...my line was loose at the damper connection from vibration...It was just hanging without wire ties...hope this helps,,,,RKL

[bill jones]

Found the problem! Vacuum pump is dying. Explains the funny growly noise coming from driver-side of the fire wall. Vacuum pump is not putting out. According to Winne, when you plug up the output of the vac. pump, it will eventually stop. Enough vacuum has been achieved and the pump should shut down. Mine would never quit. It sounded growly! Vacuum goes from pump to vacuum accumulator and then to the vacuum manifold (switch on dash).