E4 error appears and unit stops cooling, sometimes after running for a while

Safety first: Unplug the unit before cleaning or removing panels. Do not bend or puncture refrigerant coils.

• Step 1 – Clean air filter and vents:
  • Remove and wash the air filter with mild soap and water; let it dry completely.
  • Ensure intake and exhaust vents are not blocked by curtains, furniture, or walls.
• Step 2 – Inspect condenser coil:
  • Access the rear or side panel to view the condenser (hot) coil.
  • Use a soft brush or vacuum with a brush attachment to remove dust and lint from the fins.
• Step 3 – Check condenser fan operation:
  • With the unit reassembled, plug in and start cooling mode.
  • Verify that the rear fan (condenser fan) starts and runs smoothly.
  • If the fan does not run or is very slow, the Condenser Fan Motor may be failing.
• Step 4 – Portable units: verify exhaust hose:
  • Ensure the hot air exhaust hose is not kinked, crushed, or excessively long.
  • Confirm the window kit is properly installed and hot air is vented outside.

If E4 persists after cleaning and confirming fan operation, there may be a refrigerant or pressure switch issue that requires a licensed HVAC technician.