I'm no mechanic and I'm a noob Jeeper, but it just so happens that I installed an AC kit last month from jeepair.com so I think I can help for once.
The drain for your AC comes out of the firewall under your hood on the passenger side under the condensor. You might be able to clean it out from there with some creative tool making. I would think a metal coat hanger with a small hook at the end would do well. If it can't be cleared from the drain, you'll have to get your heater box out which isn't a small task. You can go to jeepair.com and download their very comprehensive installation instructions which contain color pictures and everything you need. Those pictures can help you identify the drain if needed and can also help you get your heater box out so it can be thoroughly cleaned out. Hope that helps.