Performed service diagnostic. Diagnostic found that the system was operational and was cooling. The bedroom that was not cooling was well was getting cool air however the window faces the sun from the early afternoon through sunset. I completed my diagnostic and found that the system is low on refrigerant. Options for repair were presented to the customer and they chose to have the system charged with refrigerant. 3lbs of R-410A was added to the system and is cooling at 8.7 degrees of sub cooling.