Performed furnace maintenance on 6 year old Lennox unit. Flushed condensate drain with water. Installed new owner-supplied MERV 11 filter. Inspected blower compartment, blower wheel is clean and balanced. Inspected electrical connections. Inspected flame rod. Tested resistance of hot surface igniter. Temperature rise is within limits. Removed leaves from bottom of condenser. Installed Phenomenal Aire on evaporator coil and 24v transformer in blower compartment. Upon departure system is operational.