1990 GMC SAFARI heating issue,122,000 miles 4.3 6cyl

1990 GMC SAFARI
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SAMARIAN05
  • MEMBER
  • 1 POST
Heat blows through defrost vent , but when i try to switch to optional vents i get nothing like the vents are not hooked up. All the blower speed settings work, and i still receive heat just not through any other vents.
Mar 14, 2007 at 9:25 PM
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2CARPRO JACK
  • ✓Experienced Mechanic
  • 11,533 POSTS
There is a small black plastic vacuum line that is broken. Pop the hood, the line starts at the plenum on your left, the vacuum line goes across the engine to the drivers side, it will be broken.I like to replace it completely with vacuum line instead of the plastic.
Mar 16, 2007 at 1:11 AM
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