Turn off power to the AC unit at the thermostat and breaker
Remove the access panel to reach the indoor evaporator coil
Inspect the coil for dust, dirt, and debris
Place towels or a drain pan below the coil area
Use a soft brush or vacuum with a brush attachment to remove loose debris
Apply a no-rinse evaporator coil cleaner according to the product label
Let the cleaner sit for the recommended time
Wipe accessible coil surfaces gently with a soft cloth if needed
Clean the condensate drain pan and drain line
Reinstall the access panel
Restore power to the unit
Replace or clean the air filter
Schedule professional cleaning if the coil is heavily dirty or difficult to access