Indoor unit shows F1 and unit may run erratically, not reaching set temperature.

Safety first: Disconnect power before accessing the evaporator coil.

• Step 1 – Access the coil: Remove the front panel and filters. On many Chigo models, you may need to remove an additional cover to expose the evaporator coil.
• Step 2 – Locate the coil sensor: Look for a small probe clipped to the evaporator fins with two wires leading to the PCB.
• Step 3 – Check mounting: Ensure the sensor is firmly clipped to the coil. A loose sensor can misread temperature.
• Step 4 – Test resistance: Disconnect the sensor and measure resistance. Compare to the temperature-resistance chart. Replace if open, shorted, or far out of range.
• Step 5 – Reconnect and test: Install the new evaporator temperature sensor, reassemble covers, restore power, and verify that F1 clears.