LG Air Conditioner Error Code E435

E435 is a Flow Switch Error code on LG air conditioners, typically found on water-cooled or chilled water systems. It means the control board is not detecting adequate water flow through the circuit. The unit shuts down automatically to protect internal components such as the compressor and heat exchanger. The underlying cause must be identified and corrected before the system will resume normal operation.

No. The E435 error is a protective shutdown, meaning the unit has already stopped normal operation to prevent damage. Attempting to bypass or ignore this fault could result in overheating, compressor damage, or heat exchanger failure. The system should remain off until the flow issue is properly diagnosed and resolved.

Repair costs vary depending on the root cause. Clearing a blocked strainer or opening a valve may cost only a service call fee, typically in the range of $75 to $150. Replacing a failed flow switch generally runs between $150 and $400 including parts and labor. A failed circulation pump is a more significant repair and can range from $300 to $800 or more depending on the system size and pump model.

Some causes of E435, such as a closed valve or air trapped in the piping, can be corrected without specialized tools. However, diagnosing a failed pump, faulty flow switch, or wiring fault typically requires electrical testing equipment and familiarity with hydronic systems. If you are not experienced with water-cooled HVAC equipment, a licensed technician should perform the diagnosis and repair.

A power reset may temporarily clear the error code, but if the underlying flow problem has not been corrected, the E435 code will return shortly after the unit restarts. Resetting without fixing the root cause does not resolve the fault and may allow repeated stress cycling on the components. A proper repair is required for the error to clear permanently.