Nice job on the radiator then! I have no idea what sort of tubing they use to make coils, apart from the server rooms at work I don't have any experience with air con (not much call for it most of the year in the UK) I'm guessing small cheap car radiators are harder to come by in the US, in the UK you could most likely find a smallish one without to much of an issue at a scrappy, but then their are a lot more small cars this side of the pond (sub 1 litr engines)
I break stuff.