Hello Iam new to this forum great site. My problem is when i sit air flow to come out of vent it will switch back to dash or defrost sit it on floor it will go to vent. I have checked all vacum lines dealer sold me some kind of in line small canister no luck changed out in line vacum thing by intake. No luck. When my foot is in the gas when i let off if it was on vent it will go to defrost and i hear a door close under dash. Sure could use some help Thanks.

 

IIRC, there's a vacuum line under the battery that gets corroded and breaks. When it does, then the issues like you describe appear.

 

I think that is only if you have cruise control.

 

I had this problem and it took me forever to find the leak. I checked all of the usual spots under the hood, changed the check valves, etc. and couldn't find it. I stumbled upon the leak when I was changing the upstream O2 sensor-- one of the metal lines that feed the 4WD mechanism on the front axle had a neat little slice out of it. I cut that 1" section out with a dremel then patched it with a heavy piece of vacuum tubing and small hose clamps. Problem solved.

 

mine does the same thing but as long as it blows it dont bother me lol

 

I can confirm this. I heard a hissing sound and ran my fingers along the black plastic tube and found the hole. I cut the line and fixed it with vacuum tubing. However, it didn't fix the problem with the blend door switching to defrost. Even though it was what I consider a big leak, my engine doesn't idle or drive any different.

 

An old post and an old problem for me.
However, it didn't fix the problem with the blend door switching to defrost

How do I fix the door from closing and going to defrost when I gas on it in my trk?

 

Do a search for 'wild vents'. There are a LOT of posts on that topic.

The check valve should have pretty much dealt with it. If not, you still have a leak somewhere.

 

Read this thread https://dodgeforum.com/forum/2nd-gen...ild-vents.html