This item detects ambient light and determines when headlights go on or off automatically.
Front heater core is in the dash, the rear heater core is all the way in the back of the vehicle. If you have steam coming out of the dash vents, the front HC is leaking. If you have steam coming out of the rear heater vents, then the rear core is leaking.
The flap that directs sir to the selected vents is jammed or broken...or the switch that controls it is.
what could be wrong is you might have a vacuum leak somewhere or something is disconected in the dash that switches to the vents. I had a problem with my 97 blowing air threw the floor and it was a little vacuum leak that caused it
underneath the little plastic cap thing its like black or red but on mine its right in the middle of the defog vent
the middle vents only supply air from the ac unit using a separate in dash fan. the floor and defrost vents come only from the heater
some thing is probley cloging the vents take it appart and ckeck.
No air flow? Check for vacuum leak either under dash or at engine compartment Maybe bad vacuum diaphragm under dash Maybe bad selector control
Because the vents are vacuum operated and when u floor it the motor losses vacuum
Your AC might be blowing out of dash vents on the windscreen as you might have turned the knob to that particular mode. It is also possible that the vent mechanism might be out of order or broken.
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Depending on the year. My 98 Exp EB has the knob on the dash to change the temp in the front and the console on the roof has another knob to change temps in the back
prior out with a flat screw driver