Repaired Lennox XC16 air conditioner today. Diagnosed faulty compressor contactor using Fluke 116 HVAC multimeter. Replaced with new Honeywell DP2030A5004 contactor. Recharged system with R410A refrigerant using Yellowjacket 42006 manifold gauge set. Cleaned condenser coils with Nu-Calgon 4171-75 Evap Foam. Tested amperage draw with UEi DL389 clamp meter. Verified proper operation, achieving 18°F delta T across evaporator. Completed repair in 3 hours, restoring optimal cooling performance.