heater

1994 FORD E-SERIES VAN
335,000 MILES • 6 CYL • 2WD • AUTOMATIC
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LITALIEN1001
  • MEMBER
  • 1 POST
My heater works fine but it won't switch from the defrost vents position. What could be wrong with it.
Dec 27, 2010 at 7:48 PM
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JACOBANDNICKOLAS
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 110,190 POSTS
It sounds like you have a vacuum leak. Air flow is directed by vent doors in the HVAC system. The doors are actuated by engine vacuum. If there is a leak, the defroster is the default setting. Check under the dash for leaks. With the engine running, you may get lucky and hear a hissing sound from the leak.
Jan 18, 2011 at 7:39 PM