Air Conditioning - HEIL AC unit not turning on

I noticed my AC wasn't working (although the fan was on) so I went out and checked it. It was frozen over (compressor and line going into it). I believe the problem was that the drain line was clogged so I cleared that. I checked inside the unit (opening up the top where the fan is connected to make sure air was moving around and it was clear. When I went to turn everything on, I got nothing -- it didn't even sound like it was trying to come on. Any idea what happened? It seems like I may have tripped something but I have no idea where. I checked the circuit breaker and everything else and it didn't seem like that was the problem. None of the contacts were black or looked messed up.

Thanks for any help you can give.

Only two things can cause a system to freeze: Low on refrigerant & lack of air flow thru the indoor coil. Check your air filter, make sure all registers are open & not blocked. If all is ok there, check the indoor coil to be sure it is clean as well as the fan blades.