Check Engine Light and A/C not blowing cold air

I have a 2008 C300 Sport. I am currently experiencing an intermittent check engine light and an A/C that is not blowing cold air.
The check engine light has been intermittent for about a month. After I check the gas cap, it will extinguish after awhile. The problem is that it comes back on after a few days of driving.
The A/C is really a mystery. The system is still blowing air (albeit not cold). When the car is idle, I feel warm air coming from both the driver and passenger side. When the car is in motion, I will feel cooler air (both sides). However, when I set it to Max Cool, the air on the passenger side is a lot warmer than the driver side. I can hear the compressor kick in when I turn on the A/C, so I'm at a loss on what the issue is.
I will take the car in to have the dealer check on what the problem could be, and get an estimate. But was just wondering if anyone has experienced the same.
Thanks



