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2004 Dodge Ram 2500 Question: what causes the ac vents to change from floor to panel and back by themselves



skyhawk11, 5.9L 6 Cylinder Diesel Turbo, Potwin, KS, May 12, 2014, 18:22

with ac/heater running

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  • Answer #1

    May 13, 2014, 06:04

    If vents are controlled by vacuum a loss of vacuum would cause servos to go to a rest position and usually air only comes out of floor and defrost vents. Diesel engines need a vacuum pump because they unlike a gas engine have no or very little vacuum.

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    skyhawk11, May 13, 2014, 10:41

    do you know if there is more than 1 vacuum check valve,in the system

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