LG Heat Pump Error Code Ax

The Ax code on an LG heat pump signals an EVAP IN sensor breakaway error on the indoor unit at address "x." This means the evaporator inlet temperature sensor on that specific indoor unit has come loose from its mounting position. The system flags this condition because inaccurate temperature readings from a dislodged sensor can compromise refrigerant control and system performance.

It is not recommended to continue operating the system while this error is present. A dislodged EVAP IN sensor means the control board is receiving inaccurate temperature data, which can cause improper refrigerant metering or compressor operation. Running the system in this condition could reduce efficiency or potentially cause component damage over time.

If the repair involves only reseating the sensor with no parts needed, labor costs for a service call typically range from around $75 to $200 depending on your location and the technician. If the retaining clip or the sensor itself is damaged and requires replacement, total costs including parts and labor could range from $150 to $400 or more. Getting a quote from a qualified technician after diagnosis will give you the most accurate estimate.

In some cases, a knowledgeable DIYer comfortable with opening an indoor air handler can inspect and reseat the sensor. However, accessing the evaporator section of a heat pump indoor unit often requires removing panels and working near the coil and refrigerant lines. If you are not familiar with the unit's interior layout, having a qualified technician perform the inspection and reassembly is the safer choice.

A simple power reset will not resolve the Ax error if the sensor remains out of position. The code will return as soon as the system restarts and detects the breakaway condition again. The sensor must be physically reseated in its mounting clip or bracket before the error will clear permanently.