Yesterday afternoon, I performed a full diagnostic inspection on a Lennox Elite Series central air conditioning system. I began by measuring the refrigerant charge and found it slightly low, so I added 6 ounces of R-410A to bring it up to the proper level. Next, I cleaned the outdoor condenser coil using a commercial coil cleaner to improve heat transfer. I also replaced the 1-inch MERV 8 air filter in the indoor air handler. After verifying proper airflow and cycling the system through all modes, I can confirm the Lennox AC is now operating at peak efficiency and cooling the home effectively.