Turn off power to the HVAC unit at the thermostat and breaker
Remove the access panel to reach the evaporator coil
Inspect the coil for dirt, dust, and mold
Vacuum loose debris with a soft brush attachment
Spray a no-rinse evaporator coil cleaner evenly on the coil
Let the cleaner foam and drain as directed on the product label
Wipe accessible surfaces gently with a soft cloth or brush
Clean the condensate drain pan and clear the drain line
Reinstall the access panel
Restore power and test the system
Repeat cleaning regularly to prevent buildup