Check your actuators for that or the switch may be bad. Also check for a vacuum leak
May, 23, 2012 AT 11:44 PM
I checked the actuator by pulling the vacuum line off it and it stopped operating the blend door. It appears to be o.K. The blend door operates to let the air up with the defrost setting and in the middle for the bi-level settings and the air will come out the top and the bottom. Is there is a possible second door that allows the air through the vents only? Or a fuse that operates the high setting on the switch?
May, 23, 2012 AT 11:46 PM
There are two doors one for blend and the other for the direction-vents/defrost/floor etc. It could be the control head too.