My 97 Wrangler (2.5L) air conditioning is not cold, but here's the odd thing. The lines are ice cold right up to the point where they meet the firewall. Coming out of the firewall they are not cold at all. Seems like a blockage, but I'm guessing it could be in the condenser, the dryer, or even somewhere else between the firewall and compressor. Are there any screens, orifices, or other components that tend to get blocked?