How to Keep Leaves Out of Your HVAC System

Watching leaves fall is one of the simple joys of autumn. It’s peaceful, relaxing, and a seasonal ritual in many neighborhoods – right up until it’s time to start raking. But while those colorful leaves look harmless, they can quietly cause trouble by clogging up gutters and even affecting your outdoor HVAC system.

If left unchecked, leaves can pile up, block airflow, and lead to serious performance issues with your HVAC system. Here’s how to keep them out – and what to do if they sneak in.

How Do Leaves Get Into an HVAC System?

Central air conditioning systems and heat pumps have an outdoor condenser unit located next to homes. These units work by releasing heat from inside your home to the outdoors. To do this, they draw in outside air through the sides of the unit, pass it over the condenser coil, and expel hot air through the top fan.

In the process, the airflow can pull in lightweight debris – like leaves, twigs, and grass clippings – especially if trees or bushes are nearby. Even if leaves don’t get pulled inside the unit, they can get pulled in by the wind or collect around the base, where they can block airflow and trap moisture. Over time, that build-up can lead to reduced efficiency, corrosion, or even system damage.

What Problems Can Leaves Cause?

Leaves can cause a few issues with your HVAC system, including:

• Restricted airflow: When leaves block the vents and fins of your condenser, the system has to work harder to do its job. This often leads to higher energy bills and increased strain on your equipment.
• Overheating: Reduced airflow can trap heat in the unit, which may cause overheating and even shutdowns.
• Internal damage: If leaves get inside the fan or coil area, they can damage sensitive components or clog up the drainage system.
• Rust and corrosion: Damp, decomposing leaves can hold moisture against metal surfaces, potentially leading to rust and premature corrosion.

How to Keep Leaves Out of Your HVAC System

As long as the power is off and you’re careful not to damage any internal parts, clearing out leaves and trimming nearby plants is something most homeowners can handle themselves. That said, if you ever notice strange noises, reduced cooling, or think something may have gotten stuck inside the unit, reach out to a technician.

Here’s a simple plan to keep leaves away from your HVAC system:

Avoid Leaf Build-Up

Start with prevention. Here are a few ways to keep leaves from reaching your outdoor unit in the first place:

• Clear the area regularly: Use a rake or leaf blower to clear leaves from around the base of the unit at least once a week during the fall – or more if your yard gets a lot of leaf drop.
• Create a leaf-free zone: Maintain at least 2-3 feet of clear space around the unit. This helps with airflow and reduces the chance of leaves settling nearby.
• Trim trees and shrubs: Overhanging branches and dense bushes drop leaves directly onto the unit. Trimming them back keeps debris away and makes maintenance easier.

Use a Barrier

Physical barriers can help, but they must allow proper airflow:

• Install a protective cage or screen: A fine mesh cover or cage can keep leaves out without choking the system, but don’t use anything that restricts airflow too much. Look for covers made specifically for AC units or heat pumps.
• Use a breathable cover in the off-season: If you don’t use your AC during the fall or winter, consider placing a breathable AC cover on top (never fully wrap the unit). These AC covers keep out leaves and debris while preventing moisture buildup.

Clean It Safely

If leaves have already made their way inside or around your HVAC unit, here’s how to clean it out:

1. Turn off the power. Always shut off power at the disconnect box or breaker panel before touching the unit.
2. Remove debris from around the base. Use gloved hands or a soft broom to scoop out leaves. A shop vacuum can help, too.
3. Check the top and vents. Open the top grill if you can do so safely (some are screwed in). Carefully remove any debris inside using your hands or a plastic tool (never use anything metal that could bend fins).
4. Rinse gently. You can use a garden hose to rinse off the outside fins, spraying from the inside out to push debris away.

If you’re unsure about opening the unit or feel like the leaves have caused damage, that’s a good time to bring in an HVAC technician.