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Heat/defrost on wrong route

Tiny
JOHN28759
  • MEMBER
  • 1989 CHEVROLET TRUCK
  • V8
  • 4WD
  • AUTOMATIC
  • 153,000 MILES
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?
Saturday, December 4th, 2010 AT 12:09 AM

2 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
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.
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Saturday, December 4th, 2010 AT 7:08 AM
Tiny
SHADOW1265
  • MEMBER
  • 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.
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Sunday, December 12th, 2010 AT 12:32 AM

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