1996 Chrysler LHS heater

12,100 MILES • 6 CYL • FWD • AUTOMATIC
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TIM 5
  • MEMBER
  • 1 POST
my heat works fine in the car when on mix(vent and floor) but if I have it on defrost the fan is blowing but not much coming out. All the books I have do not break down the heating system that much
Jan 12, 2010 at 2:45 AM
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ERNEST CLARK
  • ✓Experienced Mechanic
  • 1,730 POSTS
Inside of your heater module (under the dash), there's a plastic flap that's called a "Diverter door" and "Blend door".

Your unit has one Blend Door which controls the temp by mixing heated and cold air to get the right temp. I believe there are three diverter doors in your system. These doors directs the flow of air to whichever vents you have selected. (floor, dash, defrost, mix)

They are all controlled by vacuum fed to them by black plastic lines. Sometimes these lines become cracked/loose, or the diverter door will stick.

You'll have to pull your heater control unit and have a look.
Feb 10, 2010 at 9:50 PM
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