Inspect and test heating and cooling system.
Test the thermostat (warm in the winter and cool in the summer.)
Inspect and clean filters (4 times a year) and replace if necessary.
Inspect for musty orders when operating the unit.
Inspect carpet around the unit for moisture or carpet staining.
Inspect and check the coils and condensation pan. Clean according to manufacturer’s specifications.
Inspect any HVAC vents for damage, dirt or dust.
Make sure the unit operates quietly.
Source: MaintainX (Community Member)