For This job I did an evaluation on a frozen evaporator coil. When I arrived I checked the coil and filters to see if there were any restrictions. Afterwards I went outside to check the refrigerant levels and saw that they were fine on both subcool and super heat. Went back inside and double checked the delta, it was good. When I arrived the home Is owner had the door of the air handler off. I asked him if he had changed his filters today and he had. I asked him if he remembered to put the door back on and he wasn't sure. I took the door off and Ran the system to show how quickly the coil could freeze. Left the door on and left the system running for 30 minutes before Letting the customer know everything was fine.