I know this is an odd symptom and yeah I tried searching for this and didn't find anything.

1998 Ram 1500, 360, 4x4

Driving highway with the A/C on and everything was peachy. I floored it to pass someone and all of a sudden the air directionality switched from vent to floor. When my RPMs dropped after passing the air path returned to the vents.

I get that it might be a vacuum problem but what might be the source? What would re-divert with a change in vacuum? The valving in the HVAC control panel?

 

Been covered a lot. Search for "Wild Vents".
https://dodgeforum.com/forum/search....archid=3869622
https://dodgeforum.com/forum/2nd-gen...ic-please.html

 

The impression I am getting is to test and / or replace the check valves?

 

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

 

Mine did that,ended up being a rubbed line on the frame near the t/case

 

Mine was the vacuum hose elbow had dry-rotted and broke where it connected to the cruise control servo under the battery-which there was a TSB on.

 

This weekend I'll check for broken or cracked vacuum lines and I'll check the check valves. It only does it if I give it the beans so it's not really a high emergency fix.

 

I had the wild vents problem for a while, then the vents COMPLETELY stopped working. I could only turn on the defroster, or OFF. That is to say, no mattery which position I put the selector swtich in, it activated the defroster vents.

I just fixed it, after many hours of going through vacuum lines. Frustrating, all my check valves were operational, and the only leak I found was a disintegrated elbow-connector in the vacuum line under the battery (connects to the cruise control canister, I believe). Fixing this did not fix the problem though.

What was it? A LOOSE vacuum connector (multiple-line connector). The white connector behind the dash panel, that goes from the selector switch to the vacuum lines that pass through the firewall. (yes, those are vacuum lines, not electrical wires! It took me a while to realize that! ) I just unplugged the connector, and plugged it back in (took some real SQUEEZING to get it seated properly, all those gel-connectors inside of it that form a seal around the tiny little vacuum nipples inside the connector).

Now I can select defroster, dash, or floor vent. I don't know if the 'wild vents' problem is fixed though, until I drive it (that is, the problem of it changing vents while driving uphill).

I have a 2000 Dodge Ram 1500 Van. 5.2L engine V8.

 

Holy crap dude, you are really excited to share about fixing your vents. That's 5 posts- all identical- 3 of which on long dead threads...

 

+1 ... Problem is that it's not common. Most likely the previous f'd it up when installing a radio or did some other work.