air conditioning

Car: Camry 4-cycl, 1994.

I had it refilled last summer and I was surprised that it stopped working 
earlier this month. I'm not sure if it's out of refrigerant again, leaked,

or something else is broken. Are there a few steps to diagnose the 
problem. When I turn on the air, I can hear different noise like it would 
sound when working but just no cold air out. Is it possible that it wasn't

filled correctly that it was out of it sooner than it should? 

Thanks for the help,