So, yes, in conclusion these kits do work. But, it should be noted that these kits are temporary fixes to a leak in your system. If you find that your recharge your system and then a few days or weeks later it's blowing hot air again then you have a whole different problem.

Do AC recharge cans work?

Topping of your AC unit isn't a good idea because again, it is a closed system and was not designed for this. While use of these cans may temporarily solve this problem, they do not fix the leak (though some cans claim they do).

Is an AC recharge worth it?

It's also worth it because paying to have your car's AC recharged will help your AC system in the long run. You won't have to shell out additional money down the line to fix a bunch of other problems with your AC system when you spend time recharging it.