heat/defrost on wrong route

1989 CHEVROLET TRUCK
153,000 MILES • V8 • 4WD • AUTOMATIC
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JOHN28759
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  • 1 POST
I have a 1989 Cherolet pickup with factory air. When I turn on heater or defrost, all the air comes out air conditioning vents. How do I fix this?
Dec 4, 2010 at 12:09 AM
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JACOBANDNICKOLAS
  • ✓ASE Certified Mechanic
  • 110,194 POSTS
  • ASE Certified Mechanic
The airflow vents are actuated by vacuum. Check for vacuum leaks under the dash. If you are lucky, you may hear a hissing sound with the engine running.
Dec 4, 2010 at 7:08 AM
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SHADOW1265
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  • 8 POSTS
89 model has electric blend door motors. mode door motor is located on left end of heater assembly,look under dash on driver side between colum and hump.3 inch square box 1/2 inch thick easy to access.
Dec 12, 2010 at 12:32 AM
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