Cleaned and serviced furnaces. Tested flame sensors, pressure switches, hsi, fan motor amperage and capacitors, inducer motors, and gas valve voltages. Replaced furnace filters that customer provided. Replaced humidifier filter that customer provided. Cleaned out drains. Replaced flame sensor on basement unit. Everything is in adequate working condition and heating as it should. Customer will have two visits left for spring of 2024. Gave customer estimate for new furnace in basement due to the amount of rust build up.