Pkg clean and tune. Furnace clean and tune. Cycled system. Checked heat exchanger. Found all three chambers are showing rust and signs of ware. Removed and checked burners and flame sensor, both ok. Checked and adjusted gas pressures to maximize efficiency. Checked wiring and clamps. Found rust damage to blower compartment. Checked for CO and XS air levels in exhaust. Normal levels found. No CO found in airstream. Average life expectancy for this unit is 14 years. This system is showing signs of getting worn. Future failure is expected. System operating normal at this time. AC Checked indoor coil with refrigerant sniffer, no indications of leaks found at this time. Cycled system. Checked and cleaned electrical compartment. Compressor and fan motor tested lower, but within normal range. Used coil cleaner on condenser coil. Hooked up gauges and checked pressures and temps. Subcooling was 15. Indoor coil temp was 43. Checked indoor temp split, found that split to be 17. Average life ex