Unit stops cooling and displays E2; indoor fan may continue to run but compressor stops.

Safety first: Turn off power at the breaker and wait a few minutes before removing the indoor unit cover.

Steps to try:

• Access the evaporator sensor: Remove the front panel and air filters. The evaporator sensor is usually clipped to the evaporator coil or inserted into a small tube on the coil.
• Check connection: Trace the sensor wires back to the indoor PCB. Ensure the connector is firmly seated and not corroded.
• Inspect sensor and wires: Look for broken insulation, pinched wires, or a sensor that has fallen out of its clip. Re-seat the sensor firmly against the coil.
• Test resistance: With power off, disconnect the sensor and measure resistance with a multimeter. Compare to Tristar’s temperature–resistance chart (typically 5–20 kΩ at room temperature). Infinite or near-zero resistance indicates a bad sensor.
• Replace if faulty: If readings are out of range, replace the evaporator temperature sensor with a compatible Tristar part.

When to call a technician: If a known-good sensor still triggers E2, the indoor PCB sensor circuit may be defective and should be diagnosed by a technician.