LG Air Conditioner Error Code 170

Error code 170 indicates an excessive drop in low-side refrigerant pressure in the sub3 outdoor unit. The system detected that suction pressure fell below a safe operating threshold and shut off the compressor to prevent damage. The first step in diagnosis is confirming that the service valve on the sub3 unit is fully open. If it is, further refrigerant circuit diagnostics are needed.

No. The system has already shut down the compressor in the sub3 outdoor unit as a protective measure. Continuing to operate the system without resolving the underlying pressure issue can cause compressor damage and more costly repairs. The unit should remain off until the cause is identified and corrected.

A power reset may temporarily clear the error and allow the unit to restart, but the code will return if the underlying low-pressure condition has not been fixed. Resetting without addressing the root cause can lead to repeated compressor shutdowns and potential damage over time. A proper mechanical diagnosis should be completed before relying on a reset.

One step a non-technician can safely take is checking whether the service valve on the outdoor unit is in the fully open position. Beyond that, diagnosing refrigerant pressure, testing sensors, or handling refrigerant requires certified HVAC technician equipment and credentials. Attempting refrigerant work without proper tools and certification is unsafe and illegal in most regions.

Repair cost depends on the cause. If only a service valve adjustment is needed, a service call fee of roughly $75 to $150 may be all that is required. A refrigerant leak repair with recharge can range from $250 to $700 or more depending on refrigerant type and leak location. Sensor or expansion valve replacement typically falls in the $150 to $500 range including parts and labor.