LG Hvac Error Code CH02

The CH02 error code on an LG HVAC system indicates that the outdoor unit thermistor has experienced an open or short circuit condition. The outdoor thermistor is a temperature-sensing resistor that continuously monitors ambient outdoor air temperature and feeds that data to the control board. When the board detects that the thermistor signal is outside of the expected resistance range, either reading an impossibly high resistance (open circuit) or near-zero resistance (short circuit), it classifies the sensor as failed and shuts down operation to prevent potential damage from uncontrolled or unmonitored refrigerant cycling.

The most common starting point for diagnosing CH02 is inspecting the physical connections between the thermistor and the outdoor control board. The circuit connector and the lead line connecting connector can work loose due to vibration from compressor operation, temperature cycling, or handling during previous service. A connector that appears seated may still have a poor contact internally, so checking both the connector body and individual pin engagement is important. If the connectors check out, the next focus shifts to the thermistor itself and its wiring harness for signs of chafing, pinching, corrosion, or rodent damage.

If wiring and connectors are intact, the thermistor element itself may have failed. A thermistor can degrade over time due to moisture intrusion or thermal stress, causing its resistance characteristics to drift outside the acceptable window. Testing the thermistor with a multimeter at a known ambient temperature and comparing the reading against the expected resistance value for that temperature will confirm whether the component needs replacement. Operation will remain off until the fault condition is resolved and the system is reset.