Came out for 1 system maintenance. Upon arrival started at tstat turning system from ac to heat. System is a gas horizontal zoned carrier system. Insulation is good ducts are in good condition. Checked the heating sequence of the unit. Burners are firing properly all safeties are operating as designed by manufacture specifications. Did notice rust in secondary drain pan and no float safety switch on system recommend adding to prevent water damaged also recommend adding blowout kit and pan treatment into system to help keep drain lines clear. Filter is due to be changed 20x25x4. Evap coil has substantial amount of rust on coil. On outside unit system was rough on start up recommend adding hard start kit to increase efficiency and longevity of unit. Thank you for your time. Become a VIP member with 2 tuneups 10% off repairs and more Recommend adding blowout kit on drain line and pan treatment to help treat drain lines to prevent water damage