A0

Daikin External Protection Device Activated (e.g., Float Switch, External Interlock)

Daikin indoor unit stops and displays A0; may occur after service or maintenance

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.

Possible Causes

Condensate float switch triggered by high water level, External safety interlock opened, Faulty float switch wiring, Stuck or failed float switch

How to Fix / Troubleshooting

Safety first: Turn off power before opening the indoor unit or drain pan area.

Steps:

Remove the front panel and filters to access the drain pan area.
Check for standing water in the drain pan; if present, the drain line may be clogged.
Clean the drain pan and blow out or flush the condensate drain line with water or a wet/dry vacuum from the outlet side.
Locate the float switch (if fitted) and ensure it moves freely and is not stuck in the up position.

Technician tasks:

Test the float switch with a multimeter for proper open/close operation.
Repair or replace the float switch if defective.
Verify any external interlock wiring is correctly closed when safe.

Repair Difficulty

Medium 3/5

Required Part

Condensate Float Switch

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