The AC drain on a 1999 Jeep Grand Cherokee is located
underneath the passenger side of the vehicle, near the firewall. It's often a small, rubber grommet or tube. You'll likely need to get under the vehicle to locate it. It may be difficult to see without a flashlight and may require some maneuvering to find the exact spot.
Important Note: Locating the exact position can be tricky as the exact placement might vary slightly depending on trim level and specific vehicle build. A shop manual specific to your year and model would give the most precise location if you need absolute certainty.
