Is this normal for '99 Ram 1500?

When I have the a/c or fan on and accelerate really fast, the air will stop blowing out the front vents and instead blow out the vents under the windshield. As soon as I lift my foot off the gas, it returns to blowing through the front vents. Step on the gas again and it'll go back to the windshield vents.... is this normal in this truck?

Also, I have size 225/75R-16 tires on my truck. Would it be OK if I put

245/75R-16 instead? Or are they too wide for the current rims?
Reply to
Tush Smells Bush Kills!!!!!!!!
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No, it indicates either a bad check valve or a minor vacuum leak.

Reply to
TBone

Mine has done that ever since the dealer worked on the ac 3 years ago. I have no idea where to even start looking for the leak.

Reply to
RM

Most likely a vacuum leak. Most common place for a leak is the small line that runs from the manifold underneath the air cleaner to the cruise control module thats under the battery. Corrosion from the battery gets onto the line causing it to leak. Does your cruise control operate normally? On mine it would turn on indicated with the Cruise light on the dash but would not maintain speed. After replacing the line the cruise now works and my A/C vents no longer flip when accelerating.

Reply to
miles

Unfortunately it is normal. It is due to a design problem with the vacuum system. I have a '94 and it was normal on mine. Seems like Dodge doesn't like to fix obvious problems. The fix is to increase the size of the little bitty vacuum canister/check valve located on the passenger side of the intake manifold below the throttle body. I believe the replacement came from Dodge and is about the size of a 35mm film canister (stock one is about the size of the little finger). There have been a number of fixes posted that explain the procedure, including part numbers. I think the attached document has the various sources.

I upgraded the my '94 1500 to 265/R75 on the stock rims with no problems. Sure does improve the looks.

Si

Tush Smells Bush Kills!!!!!!!!!!! wrote:

Reply to
S. A. King

accelerating.

Cruise works fine on mine.

Reply to
RM

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