This is relevant to what I experienced this weekend. We went on a day trip in the Aveo yesterday and the weather was very humid and hot. The A/C worked fine when the trip started. After about 1 1/2 hours We noticed the A/C was no longer blowing very cold air. I shut it off for a while, then back on and it seemed OK. On the trip back it was doing the same thing, but now every half hour. When I parked it at home a lot of water came out of the drain, but it was also seen coming out of one of the areas near the bottom of the firewall where a bolt head is, visible under the hood.
This morning I decided to check out the A/C drain. Fortunately the drain tube is easily accessible inside the car, on the left side of the passenger area. The rubber drain tube is just a slip fit onto the plastic nipple of the A/C box. I took off the rubber drain tube and placed a 1/4" fitting into it. Then I applied 100 PSI from my compressor. Nothing but air came out of the other end. If it had been clogged, it must have drained out fully the night before. But I wanted to know where the drain exits the body of the car, and it wasn't easy to locate it. I had to jack the right side up to find it. It can't be seen from under the hood. It's a rubber body plug which is oval shaped, located on the bottom of the firewall, just to the right of the front exhaust pipe.
So you are correct. It's hard to find and tough to access the outside end. But fortunately it is very easy to work with the end that is inside the cabin.