AC goes to defrost under load

Discussion in '1997 - 2003 Ford F150 Truck Forum' started by trebot, Jul 13, 2017.

< Previous Thread | Next Thread >

  1. trebot

    Had this problem and suggestion was loss of vacuum. There is a "black box" behind battery which acts as vacuum reservoir. Suggested the box was leaking, losing vacuum and causing dash vent to default to defrost.
    Tried easy thing first. Disconnected and capped vacuum line going to box.
    It worked! Truck runs fine.
     
    trebot, Jul 13, 2017
    #1
    Tags:
    FTZ HAIC likes this.

  2. FTZ HAIC Staff Member Oregon Chapter Founding Member

    What happens now when you switch the controls from AC to fan, heat, defrost, etc?
     
    FTZ HAIC, Jul 22, 2017
    #2

  3. trebot

    Everything work fine. Motor runs great (207,000 mi). Checking fuel mileage, but seems fine.
     
    trebot, Jul 23, 2017
    #3
< Previous Thread | Next Thread >
Loading...