How to Clean the Air Filter of a Lennox Split AC System

Maintaining the air filter of your Lennox split AC system is crucial for ensuring optimal performance, energy efficiency, and indoor air quality. This comprehensive guide will walk you through the step-by-step process of cleaning the air filter, providing technical details and expert insights to help you achieve the best results.

Preparing for the Filter Cleaning

Before you begin, it’s essential to ensure that the Lennox split AC system is turned off. This can be done by using the remote control or locating the power switch on the indoor unit. Disconnecting the power source will prevent any potential safety hazards and allow you to work on the system safely.

Next, you’ll need to access the air filter. Typically, the filter is located behind the front panel of the indoor unit. Gently lift the panel from the bottom tabs to expose the filter.

Removing the Air Filter

how to clean air filter of Lennox  split acImage source: Lennox Ac by Raysonho

Carefully slide out the air filter from the indoor unit. Lennox split AC systems often have one or two filters, which can be washed and reused. Take note of the filter’s orientation and placement to ensure proper reinstallation later.

Cleaning the Air Filter

To clean the air filter, you’ll need the following supplies:
– Warm water
– Mild detergent (optional)
– Soft-bristled brush

  1. Rinsing the Filter: Hold the filter under warm running water, gently brushing it with your hands to remove any visible dirt or debris. Avoid using high-pressure water, as it may damage the filter’s delicate structure.

  2. Using Mild Detergent (Optional): If the filter is heavily soiled, you can use a mild detergent diluted in the warm water. Gently scrub the filter with a soft-bristled brush to loosen and remove any stubborn dirt or grime.

  3. Avoiding Abrasive Cleaners: It’s crucial to avoid using any abrasive cleaners or scouring pads, as they can damage the filter’s material and compromise its effectiveness.

  4. Thorough Rinsing: After cleaning, ensure that the filter is thoroughly rinsed to remove all traces of detergent or dirt. Any residual cleaning agents can potentially harm the Lennox split AC system.

Drying the Air Filter

Once the filter is clean, it’s essential to let it air dry completely before reinstalling it. Placing the filter in direct sunlight or using a fan can help speed up the drying process. Avoid putting a wet filter back into the unit, as it can promote mold growth and cause damage to the system.

Reinstalling the Air Filter

After the filter is completely dry, carefully slide it back into the indoor unit, ensuring that it is properly aligned and securely in place. Double-check the orientation to ensure the filter is installed correctly.

Replacing the Front Panel

Gently place the front panel back onto the indoor unit, making sure it is properly aligned and secured. This will help maintain the unit’s airtight seal and prevent any air leaks.

Turning the Unit Back On

Finally, turn the Lennox split AC system back on using the remote control or the power switch on the indoor unit. Verify that the system is operating correctly and that the air flow is unobstructed.

Maintaining the Air Filter

Regular cleaning of the air filter, typically every 1-3 months, is recommended to maintain the efficiency and longevity of your Lennox split AC system. Additionally, it’s advisable to schedule annual professional maintenance to clean the coils, remove debris, and straighten the coil fins, ensuring optimal system performance.

By following this comprehensive guide, you can effectively clean the air filter of your Lennox split AC system, ensuring improved indoor air quality, energy efficiency, and a longer lifespan for your HVAC equipment.


  1. Lennox Split AC Maintenance and Cleaning
  2. Lennox Split AC Filter Cleaning
  3. Lennox Owners Assistance: Air Conditioner Maintenance
  4. Lennox Split AC Coil Cleaning
  5. Lennox Split AC Fin Straightening