Performed the level 2 furnace cleaning. The unit is showing signs of wear. Heat exchanger is very rusty and chipped. I performed the heat exchanger smoke test and had a lot of back draft. No cracks located and no CO detected in the air at this time. Ventor motor, burners, and flame sensor are all starting to wear out as well. Average life of system is 12-14 years. The unit is currently 14 years of age. Due to age, condition, and cost to repair, second opinion is recommended. Furnace is currently okay to run, however, we cannot garauntee how long it will be safe and we can’t give any sort of life expectancy for the future.