F4
Mitsubishi Electric
Drain Pump / Drainage Error (Models with Built‑in Pump)
Unit shows F4 and stops; often associated with continuous drain use.
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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.
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Possible Causes
Blocked drain hose, failed internal drain pump, kinked hose, clogged pump inlet filter, pump level switch failure
How to Fix / Troubleshooting
Safety: Unplug the unit. Water may spill; have towels ready.
Steps:
- Check drain hose: Ensure the hose is not kinked, elevated too high, or blocked. The outlet should be lower than the pump discharge rating and free‑flowing.
- Clean hose: Disconnect and flush the hose with warm water to remove sludge or scale.
- Inspect pump area: Remove the water tank and access the internal pump compartment (if equipped). Clean any debris from the pump inlet and float area.
- Test pump (technician): With the unit powered and in test mode, check if the pump runs when the internal reservoir fills. If voltage is present but the pump does not run, replace the drain pump assembly.
- Check pump float/level switch: Ensure the internal float moves freely and actuates the pump. Replace the pump float switch if stuck or defective.
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Repair Difficulty
Hard
4/5
Required Part
Drain Pump Assembly
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