F3
Medisana
Ultrasonic Transducer Overheat / Dry-Run Protection Fault
Humidifier shows F3; fan may run but no mist is produced.
Advertisements
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Advertisements
Possible Causes
No water contacting ultrasonic membrane, Scale buildup on transducer, Failed transducer temperature sensor, Defective ultrasonic driver circuit
How to Fix / Troubleshooting
Safety: Unplug the humidifier before touching the water basin or transducer.
- Check water level: Ensure the tank is full and properly seated so water flows into the base. If the base is dry, clean the tank valve and base inlet.
- Descale transducer: Inspect the ultrasonic transducer disc in the base. If covered with white limescale, soak the basin area with a 1:1 vinegar-water solution for 20–30 minutes (do not immerse the entire base), then gently wipe with a soft cloth. Do not scratch the disc.
- Cool-down: Allow the unit to cool for 30 minutes, then try again. Overheat protection may reset after cooling.
- Sensor/driver check: If F3 returns quickly, the transducer temperature sensor or driver circuit on the PCB may be defective. Replacement of the ultrasonic transducer module or main PCB may be required.
Advertisements
Repair Difficulty
Medium
3/5
Required Part
Ultrasonic Transducer Module
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements