Ruud package unit not cooling

Question

I have a ruud central heat and air package unit. The air coming out of the vents is just not cool. It runs all of the time and my light bill are outragous! I had it charged with freon 2 days ago and it hasn't helped. A worker also came out to look at it and realized that a heating element was stuck on. So he was assured that it fixed it. But it didn't. It has been running all day and it is still 79 degrees in here. However it has been very hot (90-96 degrees) outside. But I still don't think that this is normal. And I've had a window unit running today. So now the guy says it may be my compressor getting old and weak and going bad, but I've heard that the compressor is either good or bad, no in between. Can anyone help?