Heater works great but it will not blow through the defrost vents?

Tiny
MWJW27
  • MEMBER
  • 1986 FORD F-150
Heater problem
1986 Ford F150 V8 Two Wheel Drive Automatic

'85 ford f-150. The heater works great but it will not blow through the defrost vents. It just keeps blowing through the dash vents. Is there a door that's not closing or some vacuum problem?
Saturday, November 15th, 2008 AT 7:33 PM

1 Reply

Tiny
DAVE H
  • MECHANIC
  • 13,384 POSTS
I would check under the hood for broken vacuum lines headed inside the cab. THis guide can help plus I have found the HVAC vacuum line diagram so you can make sure all points are getting vacuum.

https://www.2carpros.com/articles/air-vents-stay-in-the-defrost-position

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Sunday, November 16th, 2008 AT 8:42 AM

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