2000 Dodge Ram air flow from ac

2000 DODGE RAM
70,000 MILES • V8 • 4WD • AUTOMATIC
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MRSAMTZ
  • MEMBER
  • 1 POST
why does my air switch to top/defrost vents when i accelerate and go back to front vents when maintain steady speed? check valves were replaced and still have a the problem....i do hear a knocking/opening-closing sound behind the dash somewhere when i do stop accelerating....any one know anything?
Aug 11, 2008 at 5:22 PM
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MASTERTECHTIM
  • ✓Experienced Mechanic
  • 4,750 POSTS
is there a vacuum canister in that truck? sounds like losing vacuum from check valve or lack of volume in canister. can you hear anything leaking inside dash when at idle? possible leak in actuator in dash depleting vacuum source.
Aug 11, 2008 at 11:24 PM
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MRSAMTZ
  • MEMBER
  • 1 POST
no sound of leak when idle and check valves are brand new.....do hear an opening sound behind the dash when i stop accelerating though......
Aug 12, 2008 at 1:48 AM
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