the suction power seems really weak even on the max setting, doesn't pick up crumbs it used to.

Diagnosis

The loss of suction on the Dreame L20 Ultra is rarely a motor failure and almost always a result of "airflow strangulation." Because the L20 Ultra uses a high-static pressure system to pull debris from the carpet, any restriction in the vacuum path creates a pressure drop. This means that while the motor is spinning at max RPMs, the actual volume of air moving through the nozzle is insufficient to lift crumbs or heavy debris. This typically happens in one of three places: the main brush housing where hair clumps create a "plug," a saturated HEPA filter that has become blinded by microscopic dust (which prevents air from exiting the bin), or a partial blockage in the suction neck—the narrow channel between the brush roll and the dustbin. You can confirm this by checking if the robot makes a higher-pitched "whining" sound when on Max mode; this indicates the motor is working hard but the air has nowhere to go.

How to Fix It

Follow this specific sequence to restore the airflow pathway from the floor to the exhaust.

1. Clear the Main Brush Chamber: Flip the L20 Ultra over and press the release tabs to remove the main brush roll. Do not just remove the brush; reach into the chamber with a flashlight. Check the suction intake port (the rectangular hole leading to the bin) for clumps of hair or cardboard fragments. Use a pair of tweezers to pull out any debris wedged in the corners of the housing.
2. Decontaminate the HEPA Filter: Remove the dustbin from the robot. Extract the HEPA filter from the bin. Even if it looks clean, microscopic dust particles clog the pores. Tap the filter firmly against a hard surface. If you have a handheld vacuum, use it to suck the dust out of the pleats. If the filter is grey or brown, it is saturated and must be replaced.
3. Clear the Suction Neck: Use a flexible pipe cleaner or a long zip-tie to gently probe the channel between the brush housing and the dustbin. Ensure there is no "bridge" of debris blocking the passage.
4. Inspect the Side Brush: Remove the side brush screw and pull the brush out. Check the axle for wound-up hair, which can create drag and reduce the efficiency of the debris gathering process.
5. Verify Bin Seal: Inspect the rubber gasket around the edge of the dustbin. If there is a tear or a piece of debris preventing a flush seal, the robot will leak air, drastically reducing the vacuum pressure at the floor level.

If That Didn't Work

• Deep Clean the Filter with Water: If you are using the washable version of the filter, rinse it under cold water without soap. The critical step is the drying process: it must air-dry for at least 24 hours. Installing a damp filter will not only kill suction but can lead to mold growth and a "wet dog" smell during operation.
• Check for Base Station Clogs: If the robot isn't emptying properly, the bin remains half-full, which restricts airflow. Check the suction port on the L20 Ultra's empty station. Ensure the disposable dust bag is not overfilled and that the station's internal airway is clear of large debris.
• Perform a Sensor Calibration: Occasionally, the L20 Ultra's carpet detection sensors (which trigger the "Carpet Boost" mode) can get dirty. Wipe the infrared sensors on the bottom of the unit with a dry microfiber cloth. If the robot doesn't realize it's on carpet, it won't trigger the maximum suction power regardless of your app settings.
• Inspect the Main Brush Bearings: Check the plastic end-caps of the main brush. If hair has wound tightly around the bearings, the brush cannot spin at full speed, meaning it isn't "flicking" the debris into the suction stream, making the suction feel weak.

Heads Up

• Filter Replacement Cycle: Replace your HEPA filters every 3-6 months. A "clean-looking" filter can still be airflow-restricted at a microscopic level.
• Avoid Wet Debris: Never use the L20 Ultra to pick up damp crumbs or spilled liquids. This creates a "mud" inside the suction neck that hardens, permanently restricting airflow.
• Brush Maintenance: Clean the main brush roll weekly. The L20 Ultra's high power can wrap hair tightly, which creates friction and heat, potentially warping the brush housing.
• Dustbin Management: Periodically wipe the interior of the dustbin with a damp cloth to remove the fine dust film that accumulates, as this can interfere with the seal.