97 XJ, A/C blowing through def. ducts @ higher RPM

I have a 97 XJ 4.0, and @ highway speed, i.e, higher RPM's, my A/C stops blowing through my panel vents, and just directs the air onto the windshield. I have checked my vacuum canister, and it seems fine. Also, when this happens on a long trip, water starts dripping on the passenger side floor board. I have heard mention of some type of foam filter that gets clogged, and can cause this. Problem is, I cant find it! Any suggestions would be great.

Disconnect and replug the vacuum canister, and then follow the vacuum line as it goes through the engine compartment. It's pretty common for it to have holes in it near the battery.

Thanks for the info. i will give it a shot!

Mine does something similar, but it only happens at WOT.

cw50must said:

Mine does something similar, but it only happens at WOT.

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And that's STILL the symptom of a vacuum leak. You need to do what was recommended by Yucca-man to fix your problem.

Mine starts blowing thru the defroster on the highway too, and all I have to do it back off the gas for just a second and then it goes back to normal. It's a vacum thing but I havent figured out the source yet.

Also with the dripping onto the floorboard. On mine the condensation was going out the tube thru the firewall then running back on the outside of the tube, back thru the firewall and onto the pass floorboard.

I solved it by putting a rubber grommet over the tube on the outside of the firewall with some RTV to seal it up.

Thanks for the input. I have been fighting this prob for some time. I think I am getting close though.