Unit stops with E9, sometimes accompanied by water leakage from indoor unit

Safety first: Turn OFF the unit and the breaker. Be prepared for water spillage when opening the indoor unit.

Steps:

• Check drain hose: Locate the drain hose exiting the indoor unit. Ensure it slopes downward continuously to the drain point and is not kinked or submerged in water.
• Clear blockage: Use a wet/dry vacuum at the end of the drain hose outside to suck out sludge and algae. Alternatively, blow compressed air gently from the indoor side (protect surroundings from water spray).
• Inspect drain pan: Open the front panel and, if accessible, remove the lower cover to view the drain pan. Clean out slime, dirt, and insect nests.
• Check float switch (if present): Some Hitachi cassette and ducted units have a float switch. Ensure it moves freely and is not stuck in the up (alarm) position. Clean and dry it.
• Test: After cleaning, pour a small amount of water into the drain pan and confirm it flows out freely through the hose.

If E9 persists: The float switch or its wiring may be faulty and require replacement.