92 buick lesabre custom

Hi, AF new here and have seen that alot of people greatly benifit from using this forum. So can u please help me I have a 92 buick lesabre custom ac unit was running fine just low on freon replaced the freon with 3 cans and now only hot air blowing from vents. Does anyone have any ideas what the problem might be. Thanks in advance.

Welcome to AF, is the compressor running, also, you just can't routinely put in freon, what kind, r134a, is it converted for this?