2014 Chevy Sonic LT 85k Miles. Recharged the A/C because it was low. Then the problem started with hot air blowing on one side and cold air on the passenger side. Thought it was the blend door actuator, but that is working fine. Checked the charge and now it's back to being low. The A/C pump is working fine. Is there any other things to check before taking it to a mechanic?