My guess is that the answer is a simple one.
The engine and associated parts are designed to work when wet. Consider how wet your engine compartment gets when your driving in a good pouring rain, much less through standing water. Here's my thought/story...
When I first got my '01, it would chirp every time I started it but I couldn't find any issues with the belt so I figured, it's just a [Jeep] thing. I then took it to the coast and drove on the beach (something I will NEVER DO AGAIN! ['cause of the insidious nature of salt and sand]) and found that every time I ran through a wet bit, the belt would slip big time. It would, on occasions, even slip so badly that it would disable the A/C and power steering!
Once I got back to the hacienda, I took a really close look at the belt. It was not cracked or crispy or glazed or contaminated with oil or anything else I could find along those lines. What I discovered it WAS was TOO DAMNED LONG!
The PO had put on a belt that I later looked up and found was listed by the manufacturer as being proper for the vehicle but was, in fact, just barely functional. Because of the excessive length, the tensioner was at nearly full travel and the belt, where it passes near itself at the point of the tensioner, was within half an inch or so of actually touching itself. A bit of research online and I saw others had similar issues and that (at least) one brand seem to be a popular choice because it did not have that issue...Dayco.
I purchased a
Dayco Poly Rib belt # 5060883 and have not had issue one since then. As a test, I have had the engine running, with A/C on and sprayed the belt directly with a hose and it does not chirp, burp, or squeal!
Give it a shot and see if it solves the prob!