Keystone portable air conditioner shows E5 and stops cooling, often related to water tank or drainage.

Safety: Turn the unit off and unplug it before draining to avoid electrical shock and spills near live components.

Steps:

• Empty the tank: Move the unit to a location where water spills are acceptable. Remove the lower drain cap/plug and drain water into a shallow pan or tray until flow stops.
• Check continuous drain: If using a drain hose, ensure it slopes downward with no kinks and that the outlet is not submerged or blocked.
• Clean drain port: Use a small brush or pipe cleaner to clear any debris or slime from the drain outlet.
• Inspect float switch: Access the internal tank area (per manual). Verify the float moves freely and is not stuck by dirt or scale. Clean and re-seat it.
• Check wiring: Confirm the float switch wires and connector are intact and firmly connected to the control board.
• Test operation: Reassemble, plug in, and run the unit. If E5 persists with an empty tank and free-moving float, the float switch or control board input may be defective and require replacement.