Car Problem Reports

Dodge Ram 1500 HVAC Air Flow Switching to Defrost When Accelerating

Dodge Ram 1500 Problem
21 Reports
Me Too

Model Years Affected: 1994, 1995, 1996, 1997, 1999, 2000

Average Mileage: 175,200 mi (100,000 mi - 253,000 mi)


The AC/heater (HVAC) system may unexpectedly switch to the defrost mode when accelerating. This system is operated by engine vacuum and should be inspected for any vacuum leaks if this problem develops.  There is also a revised vacuum check valve available to address this concern.

  •  Rookie

    When accelerating with the AC on, the air goes from the vents into the defroster vents. I saw that you had a solution, yet it's too vague for me. Could you tell me about this revised check valve? Does it have a component name, or a part number so I can get one and get my truck fixed? Will I be able to purchase it myself? More info please. Thank you

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  • Visitor, , 195,000 mi

    HVAC Air Flow Switching to Defrost When Accelerating

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  • Visitor, , 160,000 mi

    Don't now how to fix, need help

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  • Visitor, , 141,000 mi

    havac switch to defrost when on a/c on acceleration have looked in engine compartment dont see any broken lines have any were to look

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  •  Rookie

    hvac air flow switching to defrost whe accelerating

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