Honeywell portable air conditioner shows E2 and will not cool or respond to temperature changes properly.

Safety: Disconnect power before opening the cabinet. Sharp metal edges are present inside the unit; wear cut-resistant gloves.

Steps:

• Reset the unit: Unplug for 5–10 minutes, then plug back in. If E2 reappears immediately, proceed with inspection.
• Access the evaporator: Remove the front or side panels as per the user/service manual. The evaporator coil is the cold coil behind the air filter.
• Locate the evaporator sensor: Look for a small probe clipped or taped to the evaporator fins with two thin wires leading back to the control board.
• Inspect mounting: Ensure the sensor is firmly attached to the coil surface. If it has fallen off, reattach it using the original clip or aluminum tape so it makes good thermal contact.
• Check wiring and connector: Look for chafed insulation, crushed wires, or corrosion at the connector. Reseat the connector on the main PCB.
• Test the sensor: With the unit unplugged, disconnect the sensor and measure resistance. Compare to the room sensor if they are the same type; they should be in a similar range at the same temperature. Replace the sensor if it reads open or shorted.
• Replace parts as needed: If the sensor is defective, install a new Honeywell evaporator thermistor. If a new sensor does not clear E2, the main control board is likely faulty and should be replaced by a technician.