Unit displays E9 and stops; may occur during heating mode on some AEG models.

Safety: Turn off and unplug the unit before working on the drain system. Water may spill when covers are removed.

• Check drain hose: Ensure the condensate drain hose from the indoor unit slopes downward continuously and is not kinked or blocked.
• Clear blockage: Use a wet/dry vacuum at the end of the drain hose to suck out sludge and algae. For portable units, remove the drain plug and empty the internal tank.
• Inspect drain pan: Remove the front cover and check the internal drain pan for standing water, slime, or debris. Clean thoroughly with warm water and mild detergent.
• Check float switch: Locate the float switch assembly in the drain pan. Ensure it moves freely and is not stuck in the raised (full) position. Clean and re-seat it.
• Test operation: After reassembly, restore power and run the unit in COOL mode. Confirm that water drains properly and E9 does not reappear.
• If E9 persists: The float switch may be faulty and should be replaced with a compatible AEG condensate float switch. If replacement does not help, the indoor PCB input may be defective.