LG HVAC Error Code CA

The CA code means the outdoor unit's main control board is detecting the discharge pipe thermistor as either open-circuit or short-circuit. This thermistor monitors refrigerant temperature at the compressor discharge line. The system shuts down because it cannot safely operate without a valid temperature reading from this sensor. The fault points to either the thermistor itself, the wiring, or the PCB.

No, you should not attempt to bypass or ignore the CA error and run the system. The discharge pipe thermistor protects the compressor by monitoring high-temperature refrigerant leaving the compressor. Without a valid reading from this sensor, the system cannot prevent the compressor from overheating, which can cause severe compressor damage and potentially create a safety hazard. Keep the unit off until the fault is properly diagnosed and repaired.

A power reset may temporarily clear the CA code and allow the unit to attempt a restart, but if the thermistor, wiring, or PCB has a genuine fault, the code will return quickly once the system tries to read the sensor again. Resetting does not repair the underlying electrical or component failure. The fault must be diagnosed and the defective component replaced to permanently clear the CA code.

A knowledgeable DIYer can inspect the wiring harness and connector for visible damage or corrosion, but accurate diagnosis requires an ohmmeter and the ability to test the thermistor in water at a known temperature to verify the 244,000 ohm at 20 degrees Celsius specification. Replacing the thermistor is a relatively straightforward repair, but accessing the outdoor unit's components and handling refrigerant-side parts may require a qualified technician depending on local regulations. PCB replacement, if needed, also requires correct identification of the board and safe handling of electronics.

Repair costs vary depending on the root cause. A replacement discharge pipe thermistor is typically an inexpensive part, and total repair costs including labor often range from around 100 to 250 dollars. If the PCB is the faulty component, parts alone can range from 150 to 500 dollars or more depending on the specific unit model, with additional labor costs on top. Getting a diagnostic visit from a certified technician first will clarify exactly which component needs replacement.