Turn off power to the HVAC system at the thermostat and breaker
Remove the access panel to reach the evaporator coil
Inspect the coil for dust, dirt, and mold buildup
Protect nearby electrical components with plastic or a cloth
Use a soft brush or vacuum with a brush attachment to remove loose debris
Apply a no-rinse evaporator coil cleaner evenly across the coil
Let the cleaner sit for the time specified on the product label
Wipe away loosened dirt with a soft cloth if accessible
Clean the condensate drain pan and drain line
Rinse only if the cleaner instructions specifically allow it
Reinstall the access panel
Restore power to the system
Run the HVAC system and check for proper airflow and drainage
Schedule professional cleaning if the coil is heavily soiled or difficult to access