✔ Check thermostat function
✔ Check heat exchanger
✔ Check electrical components & wiring
✔ Visually inspect for biological growth
✔ Check refrigerant levels
✔ Inspect standard air filters

✔ Check for proper air flow
✔ Flush condensate line
✔ Inspect condenser & evaporator coils
✔ Inspect safety switches/test controls
✔ Test heat function
✔ Combustion safety test

✔ Check windings on compressor
✔ Inspect ductwork
✔ Check motors
✔ Check venting
✔ Test for gas leaks