Indoor unit displays E9, unit may stop and drain pan may be full of water

Safety first: Turn off power at the breaker. Be prepared for water spillage when opening the drain pan area.

Steps:

• Inspect drain pan: Remove the front cover and check the drain pan for standing water, algae, or debris. Clean thoroughly.
• Clear drain line: Disconnect the drain hose and blow through it or use a wet/dry vacuum from the outlet side to remove clogs. Ensure the hose slopes downward continuously.
• Check float switch: Locate the float switch in the drain pan. Move it up and down; it should move freely. Clean any slime or dirt preventing proper operation.
• Test drain pump (if present): With power restored and the unit in cooling mode, observe whether the pump activates when water is present. No operation or loud noise indicates a failing pump.
• Replace components: Replace a defective float switch or drain pump with the correct Mitsubishi Electric part.