On Saturday my a/c stopped blowing air and the coil outside was frozen. I left it off overnight and it worked in the morning but went out again today Monday. The HVAC guy came and put freon in it and now it's blowing again just not cold air. What is the problem now?

Could be,, you have a leak
" ",, he put in too much freon
" ".., he ddn`t put in enough
" ",, he didn`t look for the leak

If it was low on freon, there's no doubt you have a leak,, freon doesn`t wear out or evaporate