2006 RR AC not blowing cold air

My 2006 started having problems a few months ago. My wife and I were going to a wedding and she said it was hot, my side was cool.(not cold) I felt her side and it was a lot warmer than mine. Now I don't get any cool air from either side. I had the coolant evacuated and refilled. It was a low but still doesn't get cold.

Is there a checklist I can go thru to check the system?

Thank you in advance,
Rob