Upon arrival I found a gas package unit that was in operation. I scoped the heat exchanger, and took apart to look at heat exchanger, found no cracks, some rust on inside of tubes but nothing showing signs of cracks yet, still has good life in the heat exchanger. Checked blower wheel and indoor coil cleanliness and found both basically spotless. Filter inside dirty though. (20x25)Started system in heat and checked gas pressure and ensured heat cycle worked properly, as it did. Then I crawled under crawl space and checked out ductwork, all hardpipe ductwork, and good sealed connections with proper insulation. Since weather was nice today I tested out ac, ensured it cycled on and checked delta T, right around 15 degree difference from return to supply. Delta T with furnace was 34. I would recommend cleaning the outdoor coil on the system and signing up for protection plan which will provide maintenance this system needs to run a good life for you. Overall heat and cool worked and system