my roomba 694 is leaving a trail of dust behind it, not picking anything up.

Diagnosis

The Roomba 694 is designed as a mechanical-lift system; it relies on the synergy between the dual multi-surface brushes and a vacuum motor to pull debris into the bin. When it leaves a trail of dust, it means the "vacuum" part of the equation has failed, turning the robot into a simple pusher. This is almost always caused by a restriction in the airflow path. If air cannot flow freely from the floor, through the brushes, and out the exhaust, the motor cannot create the pressure differential needed to lift fine dust particles. The most common culprit is a saturated AeroVac filter. Over time, microscopic dust particles embed themselves into the filter pleats, creating a wall that blocks air. When the filter is clogged, the motor spins, but no air moves, leaving the debris exactly where the brushes flicked it. Alternatively, a partial blockage in the intake throat—the narrow passage between the brush deck and the bin—can cause debris to "back up," resulting in a trail of dust being dragged along the floor. You can confirm this by checking if the exhaust vents on the sides of the robot feel unusually cool or if the motor sounds higher-pitched than normal during a cleaning cycle.

How to Fix It

Follow these steps in order to restore full suction power to your Roomba 694:

1. Clear the Bin and Intake: Press the release button on the rear of the chassis and slide the debris bin out. Empty the contents into a trash can. Use a flashlight to look into the "throat" of the robot (the opening where the bin slides in). If you see a clump of hair or a piece of cardboard wedged there, use a pair of tweezers or a long needle-nose plier to remove it.
2. Deep Clean or Replace the Filter: Remove the white pleated filter from the bin. If it looks grey or brown, it is saturated. Tap it firmly against a hard surface to knock out loose dust. For a deeper clean, use a soft brush or a vacuum cleaner with a hose attachment to suck the dust out of the pleats. If the filter is over six months old, discard it and install a fresh Genuine iRobot replacement filter.
3. Service the Brush Deck: Flip the robot over and press the tabs to remove the grey brush guard. Pull out both the green rubber extractors and the yellow bristle brush. Use the provided cutting tool to remove all hair and string wrapped around the axles. If the brushes are heavily worn (bristles are splayed or rubber is torn), they will no longer "kick" the dust upward into the suction path and must be replaced.
4. Clean the Sensors: Use a clean, dry microfiber cloth to wipe the cliff sensors on the bottom perimeter. While not directly related to suction, dirty sensors can cause the robot to stutter or change direction frequently, which often looks like "missing" spots of dust.

If That Didn't Work

• Check for Air Leaks: Inspect the rubber seal around the debris bin. If the bin is not seated perfectly or if the seal is torn, the vacuum will pull air from the sides of the bin rather than from the floor. Ensure the bin clicks firmly into place; if it feels loose, the latch may be worn, requiring a bin replacement.
• Inspect the Exhaust Path: Check the exterior vents on the sides of the Roomba. If these are clogged with pet hair or lint, the motor cannot push air out, which kills the suction at the bottom. Use a can of compressed air to blow out the side vents.
• Perform a Soft Reset: Occasionally, the software may not be ramping up the motor speed correctly. Hold down the CLEAN button for 10 seconds until the light ring flashes, then let go. This resets the motor controller and can sometimes restore optimal suction levels.
• Verify Brush Rotation: With the robot off, manually spin the brushes. If they feel stiff or "crunchy," there may be debris wrapped around the internal motor gearboxes that you cannot see. This prevents the brushes from spinning at the RPM required to lift dust.

Heads Up

• Filter Maintenance: Never wash the AeroVac filters with water. Wetting the filter material causes the fibers to shrink and tighten, which permanently blocks airflow and can lead to motor burnout.
• Brush Replacement Cycle: Replace the yellow bristle brush every 3-6 months. Once the bristles wear down, the "flicking" action is lost, and the robot will leave fine dust behind regardless of how strong the suction is.
• Bin Capacity: Do not let the bin fill past the "MAX" line. When the bin is overfilled, the distance between the debris pile and the filter becomes too small, effectively choking the vacuum motor.
• Surface Warning: Avoid using the 694 on high-pile shag carpets. The brushes can get bogged down, reducing the speed of the agitation and leaving streaks of dust in the carpet fibers.