2 system Home Care - (2) 16 year old carrier Gas Furnaces with AC & Coils I cycled in each system from the thermostat, took amp/electrical readings, temperature differentials, tested all components for ignition system, blower motor, and inspected coil, blower wheel, and heat exchanger. All parts are original and outdated. Due to the age, normal wear, and condition, all parts are subject to failure at this time. The heat exchanger is compromised with a couple small cracks and lots of hot spots, fatigue, and thinning. The heat exchanger gets direct heat from the flame and it expands while heating up them contracts when cooling back down at the end of a heat cycle. In the winter time these furnaces run up to 20-30 heat cycles per day. In doing so the metal can only take expanding and contracting so many times before it starts to crack, thin out. At almost 16 years old given the current condition of this heat exchanger, I recommended updating this equipment as it has reached its safe h