Hello,

My old Schrader valve core was leaking bad in the A/C low pressure port of my 1999 Cherokee Classic. I Can't find a replacement anywhere to save my life. I bought two different ones that at the store showed up as the correct replacement for my car but they don't fit. Unfortunately I lost my old one.. I thought there was no pressure whatsoever left in the system, but as soon as I unscrewed it there was just enough to shoot it away who knows where, on the grass.

 

Might be a good idea to just head to the junk yard and find one. If that one leaks, at least you have one to compare to.

 

So, as a last hope before hitting a junkyard or a shop's dumpster looking for a/c hose assemblies, I drove a 40 miles round trip to NAPA... theirs is the right one, it works.
They sell the whole valve for 9 bucks, if you just need the core all you gotta do is pull the core out with the valve core tool and that's it.
If you still have a OEM A/C hose assembly DO NOT buy the kits from O'Reilly, Autozone and Advance with the brass-looking valves... they look very similar to the original thing, but I promise you that at least the one for the service port (low pressure) will NOT work on a '99 Cherokee (haven't tried high pressure side as I don't need to mess with it).
Just in case anyone ends up in this thread later on looking for the same thing, I will post the part # here later... (I left the packaging downstairs in the car). Hopefully it'll save someone else from a big headache someday.

 

A/C Service port valve assembly (for 1999 Cherokee)
NAPA PART #409575 #59973 (there are 2 numbers on the box, the first is on top the other below it)

 

I made an account just to say this helped me, I have the exact same issue on my 99