Came out for 1 system maintenance. Upon arrival started with indoor upflow gas unit, our install. Customer changes filters themselves, checked all heating elements to verify proper heating sequence. All safeties are operating as designed, burners are firing properly. Washed out unit and checked all electrical components. All components are operating as designed. Recommend adding pan treatment into system to treat drain line to help prevent issues from occurring. Also recommend adding hard start kit and surge protection to improve longevity of system and to protect unit. Thank you for your time. Pan treatment