And your a/c works if you run the defroster.
Check the passenger side of the firewall, down low, you should see a rubber hose coming out of it, most likely with a 90 degree bend in it. It's short and just ends, not connected at the other end to anything. That's your a/c drain. Check it to see if it might not be partially blocked or pinched shut. Could be that it's blocked up slightly or pinched, and the evaporator case is filling up with water until there is enough to push past the restriction.
97 Sahara, 74 Renegade, 72 CJ5, 55 Willy's (the Beast) Boss 302, 6:34 gearing, Bose 901 speakers.
God I miss that Jeep. Forgot the kinda Jeep, 80 SX4.