Turn off power to the HVAC system at the breaker
Remove the old thermostat cover
Take a photo of the existing wire connections
Label each wire by its terminal letter
Remove the old thermostat base
Check the new thermostat’s wiring diagram
Mount the new thermostat base on the wall
Feed the wires through the base opening
Connect each wire to the matching terminal
Tighten all terminal screws securely
Attach the thermostat faceplate
Restore power at the breaker
Set up the thermostat according to the manufacturer’s instructions
Test heating and cooling functions
If wires do not match standard terminals, consult an HVAC professional