Heater control valve

2002 FORD EXCURSION
140,000 MILES • 6.8L • V10 • 4WD • AUTOMATIC
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NMARTINEZ
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  • 1 POST
Heater control valve , the vacuum line connected to it always has vacuum , it wont allow the valve to open. I unplugged the line to it then it opens and let's hot go through , what makes vacuum to this line ?
Sep 20, 2016 at 6:56 PM
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CARADIODOC
  • ✓ASE Certified Mechanic
  • 34,321 POSTS
  • ASE Certified Mechanic
The vacuum is switched at the heater controls. The valve blocks coolant flow when you are running the AC so it does not have to work so hard to cool the air. The AC runs in defrost mode too to remove moisture from the air before it gets blown onto the cold windshield where it would condense, but the heater control valve stays open in that mode so the air gets warmed up.
Sep 21, 2016 at 1:25 AM
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