my purifier turns off by itself after a few hours on timer mode, but i didn't set a timer.

Diagnosis

The Medify MA-40 V2.0 is experiencing an automatic power-down sequence caused by the activation of the "Child Lock" safety mode. While this feature is primarily designed to prevent accidental setting changes by children, it triggers a hard-coded safety timeout on the V2.0 logic board. When this mode is active, the unit is programmed to shut off completely after 8 hours of continuous operation to prevent the machine from running indefinitely in an unattended environment. You can confirm this is the issue by looking at the LED control panel. If the padlock icon is illuminated or if the buttons on the top interface do not respond to single presses, the Child Lock is engaged. This often happens accidentally during cleaning or when the unit is bumped, as the specific button combination required to toggle the lock is easily triggered by simultaneous pressure on the touch-sensitive panel.

How to Fix It

To disable the Child Lock and stop the automatic 8-hour shutoff, follow these precise steps on the top control interface:

1. Ensure the unit is powered on and plugged into a grounded AC outlet.
2. Locate the 'Light' button (used for dimming the display) and the 'Fan Speed Down' button (the arrow pointing down).
3. Press and hold both the 'Light' button and the 'Fan Speed Down' button simultaneously.
4. Maintain firm pressure for exactly 3 to 5 seconds. Do not release the buttons until you see a visual change on the display.
5. Verify that the padlock icon has disappeared from the LED panel.
6. Set your desired fan speed (Low, Medium, or High) to resume normal operation. The unit will now run continuously until manually turned off.

If That Didn't Work

• Perform a Hard Power Cycle: Unplug the MA-40 from the wall outlet for at least 60 seconds. This clears the volatile memory on the control board and resets any temporary software glitches that may be mimicking a timer shutoff. Plug it back in and immediately check if the padlock icon is off.
• Check for Filter Saturation: If the HEPA filter is severely clogged (indicated by a "Change Filter" alert or significantly reduced airflow), the motor can overheat. The MA-40 V2.0 has an internal thermal cutoff switch that will kill power to the motor to prevent a fire hazard. Replace the H13 HEPA filter if it has turned dark grey or black.
• Inspect the Power Cord and Socket: Ensure the power cable is seated firmly into the base of the unit. A loose connection can cause intermittent power loss that looks like a timed shutoff, especially if the unit vibrates during high-speed operation. Try a different wall outlet to rule out a tripped GFCI outlet or a faulty surge protector.
• Verify Timer Settings: Though you mentioned not setting a timer, press the 'Timer' button repeatedly to cycle through the 2h, 4h, and 8h options. If the timer light is blinking, the unit is in a countdown mode. Press the Timer button until the timer indicator light turns completely off.

Heads Up

• Filter Seating: Always ensure the filter is seated flush against the internal housing; an air gap can cause the motor to work harder, increasing heat and triggering the thermal shutoff.
• Placement: Keep the unit at least 15 inches away from walls or curtains to ensure the intake vents aren't obstructed, which prevents overheating.
• Cleaning: Use a vacuum with a brush attachment to clean the exterior pre-filter every 2-4 weeks to maintain optimal airflow and longevity of the motor.
• Power Strips: Avoid plugging the MA-40 into low-quality power strips; use a high-quality surge protector to prevent voltage spikes from corrupting the control board settings.