Car Problem Reports

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

Dodge Ram Van 2500 Problem
28 Reports
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Model Years Affected: 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003

Average Mileage: 126,062 mi (22,000 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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  •  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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  • , , 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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  • , , 53,000 mi

    HVAC Air Flow Switching to Defrost When Accelerating

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  • , , 160,000 mi

    Back fire during start like a 3 pop, pop pop, then It seems to idle ok for a sec and then the lAg of and bucking and low horse power. Just changed water pump and radiator and over heats in weird and different times. Replaced thermostat also!! Fuel runs rich also please help. Oh yea the defrost to vent switch problem also exists

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  • , , 22,000 mi

    When running either the heater or AC and go to accelerate, the airflow will switch from blowing out the front vents to the floor, or defroster vents with no consistency until up to normal speed or you take your foot off the gas. Even when at normal speed and it is blowing out the front vents and you even push on the gas a little it will switch again to the different vents...

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  • , , 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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  • , , 123,000 mi

    Same problem with 2000 DODGE Ram 1500 Laramie, no backfire problems and runs great {318 ci), just aggravates the ---- out of me. You can hear the flapper switch and drop back when acceleration stops and air resumes correctly. Haven't fixed yet, winter is almost here, hope heater is not affected by problem.

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  • , , 100,000 mi

    Bought it 6 months ago, since Dodge is famous for electrical problems I thought that was it, I will check for vac leaks.

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  • , , 80,000 mi

    AC air flow switches to defrost when accelerating or going up hill.

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