Diagnosis
This behavior is not a hardware failure, but rather the activation of the iRobot "Dirt Detect" technology. The iRobot Roomba i3+ is equipped with acoustic sensors that monitor the volume of debris entering the vacuum bin. When the robot detects a high concentration of dirt, dust, or pet hair in a specific area, it triggers a localized cleaning cycle. The flashing blue light ring serves as a visual indicator that the robot has transitioned from its standard navigational path to a high-intensity cleaning mode. The "circling" motion you are seeing is the robot performing a spiral pattern to ensure maximum suction and brush agitation over the dirty patch. This process continues until the acoustic sensors report that the debris levels have dropped below a specific threshold. You can confirm this is happening by observing the robot's behavior: if it returns to its normal linear path once the "dirty" spot is cleared, the system is functioning exactly as designed. If the robot continues to circle indefinitely in a clean area, it indicates a sensor obstruction rather than a Dirt Detect event.
How to Fix It
Since this is a built-in feature and not a malfunction, the "fix" is to allow the robot to complete its cycle. However, if you want to stop this behavior or ensure it is working efficiently, follow these steps:
- Allow the Roomba to finish the spiral pattern. It typically takes 30 to 90 seconds per "dirt patch" before it resumes its mapped route.
- If you wish to override the Dirt Detect mode and force the robot back to its regular path, press the "CLEAN" button once. This will cancel the current localized spiral and prompt the robot to recalculate its route.
- Check the debris bin. If the bin is nearly full, the sensors may trigger "Dirt Detect" more frequently because the airflow is restricted, making the robot "think" it is still encountering heavy debris. Empty the bin manually or dock the unit to the Clean Base for an automatic empty.
- Inspect the two side-bristles. Ensure the rotating side-brush is not tangled with long hair or string, as this can sometimes cause the robot to pivot erratically, mimicking a spiral.
If That Didn't Work
If the robot continues to spin in circles on a clean floor or the blue light persists without a clear cause, try these alternatives:
- Clean the Acoustic Sensors: Use a can of compressed air or a dry microfiber cloth to clean the sensor ports located near the vacuum intake. Dust buildup in these ports can trick the robot into thinking it is constantly detecting debris, causing it to stay in a permanent spiral loop.
- Check for "Ghost" Obstacles: Ensure there are no highly reflective surfaces (like chrome furniture legs or mirrors) or deep black rugs in the area. The i3+ uses infrared sensors for cliff detection; certain dark colors or reflections can trick the robot into thinking it is at an edge, causing it to pivot and circle in place.
- Perform a Hard Reboot: Press and hold the "CLEAN" button for 20 seconds until the light ring swirls. Let go, then wait for the robot to reboot. This clears the temporary cache and resets the sensor calibration.
- Inspect the Caster Wheel: Flip the robot over and remove the small front omni-wheel. If hair or grit is jammed in the axle, the robot cannot move in a straight line and will naturally drift into a circle, which the software may misinterpret as a Dirt Detect event.
Heads Up
- Avoid using "wet" mopping sprays on your floors before running the i3+, as the liquid can clog the acoustic sensors and trigger false Dirt Detect alerts.
- Regularly check the main rubber extractors (the two large rollers). If they are worn down or clogged with hair, the robot may struggle to pick up debris, causing it to stay in the blue-light spiral mode longer than necessary.
- If you notice the blue light is a solid spiral rather than a flashing one, you have accidentally activated "Spot Clean" mode, which cleans a 3-foot diameter area regardless of whether dirt is present.