Unit stops and displays E4, often after running for some time; may be accompanied by water in the base pan.

Safety: Turn the unit off and unplug it before draining water to avoid electrical shock.

Steps:

• 1. Drain the unit: Move the portable AC to a location where water spillage is acceptable. Remove the lower drain cap and attach a suitable hose if provided, or place a shallow pan under the drain. Allow all water to drain completely.
• 2. Check for blockages: Inspect the drain port and any attached hose for slime, debris, or kinks. Clean with warm water and a small brush if needed.
• 3. Inspect float switch: Remove the rear panel to access the internal condensate tray. Locate the float and float switch assembly (usually a small plastic float that rises with water level and a micro-switch or magnetic reed switch).
• 4. Test float movement: Manually move the float up and down. It should move freely and click the switch or change continuity. Clean any algae or dirt that may cause sticking.
• 5. Electrical test: With the unit unplugged, disconnect the float switch and test continuity with a multimeter while moving the float. Replace the float switch if it does not change state.
• 6. Reassemble and test: Reinstall panels, plug the unit back in, and run in COOL mode. If E4 clears and does not return, the issue was likely a full tank or blockage. If it returns immediately with an empty tank, the float switch or PCB input may be faulty.