Change or clean customer-provided air filter

Check thermostat and mounting and adjust if necessary

Calibrate thermostat (if applicable)

Check system for proper refrigerant charge

Check return air supply temperatures and split

Check for proper airflow

Check electrical wiring connections and re-secure if needed

Check all electrical components

Check drain pan and flush drain

Check and clean indoor evaporator coil in place if accessible

Check cabinet insulation for mold, mildew, and adhesion

Check blower wheel for buildup of dirt and mildew

Check heat strips

Check voltage and amperage draw on components

Test float switch (if applicable)

Check capacitors for starting capability

Check contactors for starting capability

Clean and flush condensate drain lines

Check fan motors on indoor and outdoor units

Spray disinfectant cleaner on evaporator and air handler cabinet

Install algaecide tablets in drain pan for drain line

Clean furnace and condenser exteriors

Test safety controls

Check and adjust burners

Visually inspect heat exchanger

Check all caps and valves for secure seals

Check final performance and suggest necessary improvements