Car Problem Reports

Dodge Ram Van 2500 HVAC Air Flow Switching to Defrost When Accelerating

Dodge Ram Van 2500 Problem
18 Reports
Me Too

Model Years Affected: 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003

Average Mileage: 137,444 mi (53,000 mi - 265,000 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 I accelerate the a/c switches to floor and then defrost mode. I have replaced the check vavle and have checked all my vaccum lines and have found no leaks, but the problem is still there. Any Ideas.

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  • Visitor, , 74,000 mi

    Daytona Dodge just wants to keep changing the front resister even after being told precisely what the problem is. Then just hands me the key, I start the van and NOTHING has changed except for the amount of $$ in my bank account. I told the owner about it and was treated like I was the liar when in fact they are the ones who passed it off to me as fixed. Was able to get $100 returned off bill and was asked to never come back to his dealership because I had initially said that whoever claimed to have fixed the problem must have lied. I'll make the 20 mile trip to New Smyrna Dodge for all my work from now on. Problem still exists as of 4/07/2013 and the fan speed only works in the high position. Any vacuum diagrams for this vehicle?

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  • Visitor, , 109,000 mi

    Air or heater will switch to Defrost area during hard acceleration or load going uphill. Have not diagnosed or solved yet.

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  • Visitor, , 53,000 mi

    HVAC Air Flow Switching to Defrost When Accelerating

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  •  Rookie

    My air flow switching to defrost when i accelerating. Also i can not get any heat only cool air for heat i Replace the heat control and the themostate i am thinking it may be the vacuum help

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  • Visitor, , 265,000 mi

    Heater switches to defrost during acceleration

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