Try a reverse flush.

How did it turn out? I had the same issue bad in December and did a reverse flush of the core and system. It actually didnt help. It started working when I installed an exhaust system. I guess something loosened up when I was banging around under the jeep trying to get the stock exhaust out. Good luck.

I have read that a lot of Jeep owners have problems. I do not understand why a manufacturer would make such a carppy part and then bury it behind the dash where it requires a whole day to change one. I had to change one that was leaking in a 87 F150 but it was 10 years old and never clogged up. I just took the glove box door off an d was done in an hour. Since changing one has become such an arduous task I would think that manufactures would design them to last a while. I have heard of Jeeps under warranty with bad ones. I guess the daughter will be wearing her long handles for awhile.

Cut my fingers to shreds changing 2 heater cores on my 89 F-150 behind the glove box. OE started leaking at 75k. First replacement lasted 2 weeks, Advanced AP replaced defective core, second replacement was going strong at 120K when I got rid of the truck.