How to Clean Air Conditioner Coils

Dirty AC coils are one of the leading causes of poor cooling performance and high electricity bills. When the evaporator or condenser coils are coated in dust, dirt, and grime, heat transfer is blocked and your system has to work much harder. Cleaning them yourself is straightforward and can make a noticeable difference in performance.

Two Types of Coils

• Evaporator coils: Located inside the indoor unit. They absorb heat from the room air. Tend to collect dust and mold.
• Condenser coils: Located in the outdoor unit. They release heat outside. Tend to collect dirt, leaves, and debris.

Both should be cleaned at least once a year — ideally before the cooling season starts.

What You'll Need

• AC coil cleaner spray
• Fin comb
• Soft brush or vacuum with brush attachment
• Compressed air duster
• Garden hose (for outdoor unit)
• Gloves and safety glasses

How to Clean Evaporator Coils (Indoor Unit)

1. Turn off power at the breaker before starting.
2. Access the coils by removing the front panel and filter of your indoor unit.
3. Vacuum loose dust from the coil surface using a soft brush attachment.
4. Apply coil cleaner: The Essential Values AC Coil Cleaner (Gallon) is a non-foam, professional-grade formula that works on both evaporator and condenser coils. Spray it evenly across the coil surface and let it penetrate for 5–10 minutes.
5. Rinse carefully with a spray bottle of clean water, or let the condensate from normal operation rinse it during the next run cycle.
6. Straighten bent fins with a fin comb. Bent fins restrict airflow and reduce efficiency. The Boao 2-piece set covers different fin spacings and works on both evaporator and condenser coils.

How to Clean Condenser Coils (Outdoor Unit)

1. Turn off power at the disconnect box near the outdoor unit.
2. Clear debris — remove leaves, grass, and dirt from around and inside the unit.
3. Blow out loose debris with a WOLFBOX MegaFlow Electric Air Duster. At 110,000 RPM, it blasts dust and debris from between the fins without the waste of disposable cans.
4. Apply coil cleaner to the fins, working from top to bottom.
5. Rinse from the inside out using a garden hose on a gentle setting. Never use a pressure washer — it will bend the fins.
6. Straighten any bent fins with the fin comb.

How Often Should You Clean AC Coils?

• Evaporator coils: Every 6–12 months
• Condenser coils: Once or twice a year, more often if surrounded by trees or vegetation
• After any major dust event (construction nearby, heavy pollen season)

Signs Your Coils Need Cleaning

• AC runs longer than usual to reach set temperature
• Electricity bill has increased without change in usage
• Ice forming on the indoor unit (frozen evaporator coil)
• Warm air blowing from vents despite AC running
• Musty smell when AC is on

Clean coils can improve your AC's efficiency by 5–15% and significantly extend the life of the unit. It's one of the highest-impact maintenance tasks you can do yourself.