In my state, one can't buy their own freon so I've never seen cans of 134a either. I assume that they're 1 lb cans like R12? If so and you added 2 lbs, you now have too much freon in the system and that's as bad as not enough. The proper charge is 1.63 lbs (by the book) so you should have your system recovered with the proper charge then added to be sure. That's probably why your AC compressor isn't cycling now and it should be normally. If there's too much freon, not only will the system not cool as well as it should but if the pressure gets too high, it'll all blow out the compressor relief valve.