Verify local permits, codes, and manufacturer requirements
Gather tools, materials, and safety gear
Choose indoor and outdoor unit locations
Check wall structure, clearances, drainage, and line-set path
Turn off power at the breaker
Mount the indoor unit bracket level on the wall
Drill the wall penetration for refrigerant lines, drain, and wiring
Install the condensate drain line with proper slope
Run the refrigerant lines, communication cable, and power wiring
Mount the outdoor condenser on a pad, stand, or brackets
Secure and level the outdoor unit
Connect refrigerant lines to both units
Tighten flare fittings to specification
Connect electrical wiring according to the wiring diagram
Install line-set insulation and seal the wall opening
Vacuum the refrigerant lines with a vacuum pump
Perform a leak test
Open the service valves to release refrigerant
Restore power to the system
Test cooling and heating operation
Check airflow, drainage, noise, and error codes
Seal and finish all exterior and interior penetrations