Upon my arrival I evaluated 1 Lennox heat pump system. I verified system safety and performance is to manufacture specifications. Flushed and treated the water removal system. Cleaned the electrical cabinet and washed unit using water. Found the auxiliary heat kit to be not working. Upon my diagnosis I found the heat sequencer to be stuck closed, not giving power to the heating elements. Informed customer of my findings and customer chose the HD5A option. Replaced faulty heat sequencer, and tested system for performance and safety. Let dust burn off of heating elements to prevent smell/smoke. No other issues/recommendations at this time. System performing to manufacturer specifications at this time.