Blower will switch from the vents to the defrost vents

Tiny
DALE OWEN
  • MEMBER
  • 2001 FORD F-150
  • V8
  • 2WD
  • AUTOMATIC
  • 135,000 MILES
While AC is running, when I accelerate the blower will switch from the vents to the defrost vents, then back again when I let off the accelerator. What is causing this problem and is it expensive to repair?
Do you
have the same problem?
Yes
No
Friday, August 15th, 2008 AT 1:36 PM

1 Reply

Tiny
MERLIN2021
  • MEMBER
Find the vacuum line that comes out of the firewall, this is the supply line, and it goes to a small reserve tank in the engine compartment or under the das, then anothe line goes from the tank to a check valve, then to manifold. If the reserve tank cracks, or the supply line breaks, air will divert to the defrost vents when accelerating. The reserve tank supplies needed vacuum to A/C system during these times! Mot expense, usually the check valve or tank...here's a vacuum schematic:


https://www.2carpros.com/forum/automotive_pictures/62217_F150a_2.jpg



https://www.2carpros.com/forum/automotive_pictures/62217_F150b_2.jpg

Was this
answer
helpful?
Yes
No
Thursday, July 30th, 2020 AT 11:49 AM

Please login or register to post a reply.

Sponsored links