Completed furnace maintenance and inspection. I checked all amp draws and components. I tested airflow and temps splits. I cleaned up flame sensor. Customer notified me that the furnace was not efficient and was racking up his bill. I looked further into that and found that the blower speeds were set too low which was causing the furnace to have to run all the time to heat the home. I fixed blower speeds and adjusted gas pressures to have a 50 degree temp split I stead of being at the max temp split of 65. I notified customer of adjustments and the furnace was heating the home much better at departure. After fixing the furnace issues my only main concerns air the ac and water heater. The water heater is 26yrs old and not in good condition. It has signs of leaks and the flames have back drafted. The ac is 18 yrs old and uses R22 refrigerant. This refrigerant is no longer manufactured as of January of 2020. Any repairs that would include refrigerant on this unit could be very expensive.