Diagnosis
The loud, distinct clicking or buzzing from the rear of your LG LP1419IVSM is almost certainly the inverter board's relays engaging and disengaging. This is a normal operational sound for this dual inverter portable AC. Unlike traditional compressors that simply turn on at full blast and off, your inverter compressor modulates its speed for precise, efficient cooling. The relays on the circuit board are the switches that manage this precise power control, and their operation can be audible.
How to Fix It
No repair is required, as this is by design. The sound indicates the unit is actively and efficiently regulating its cooling output. You cannot and should not try to silence these relays. To minimize disturbance, ensure the unit is on a stable, level surface, as vibration can amplify the sound. Positioning the AC farther from where you sleep or relax can also help.
If That Didn't Work
If the clicking becomes a constant, rapid chatter or is accompanied by a complete loss of cooling, an error code on the display (like "CH" or "PS"), or a loud electrical hum, there may be a fault. First, unplug the unit for 5 minutes, then plug it back in to reset the control board. If the problem persists, the inverter board or compressor itself could be failing. At this point, you must stop using it and contact LG support for warranty or repair service, as these are complex components.
Heads Up
This relay noise is most pronounced in quiet environments and during the compressor's low-speed modulation phases. It is not a sign of a malfunction or impending failure on the LP1419IVSM model, but an inherent characteristic of its advanced dual inverter system. Attempting to open the cabinet voids your warranty and exposes you to high-voltage components.