Refrigerant Shortage

What it means

This code appears on LG inverter split air conditioners and on LG ducted and cassette units that use CH codes. It means the unit concluded from its temperature sensor readings during operation that the refrigerant charge is too low. It stops the compressor to protect it, because running short of refrigerant makes it overheat and lose lubrication. Low refrigerant almost always means a leak, which a licensed technician must find and repair before recharging. The same code can mean something else on other brands.

Models covered: LG inverter split air conditioners (e.g. Dual Inverter) and LG ducted/cassette units that use CH codes; the code shows as CH plus a number on the display or as LED blinks.

Related codes: CH32CH46CH02CH06CH61

Symptoms4

• Cooling gets weaker over days, then CH38 shows and the compressor stops.
• Frost or ice on the small pipe or on the outdoor unit service valves.
• Oily spots at pipe joints or under the indoor or outdoor unit.
• The code sometimes appears after a new installation or after the unit was moved.

Possible causes6

• Leak at a flare joint on the indoor or outdoor unit, the most common cause.
• Leak in the evaporator or condenser coil from corrosion or a pinhole.
• Leak at the outdoor unit service valves or their caps.
• Service valves not fully opened after installation, or an undercharge for extra pipe length.
• Blocked electronic expansion valve or strainer that looks like a shortage.
• A pipe sensor misreading and making the unit judge the charge as low.

How to diagnose5

1. Switch off at the breaker and look at the joints under the indoor unit and at the outdoor unit for oil spots or frost.
2. A technician measures pressures and pipe temperatures while running and compares them with LG specification to confirm a low charge.
3. Confirm the service valves are fully open, especially after a recent installation or move.
4. Search for the leak with an electronic detector or soap bubbles, and pressure-test with nitrogen if needed to locate it.
5. If the charge is not actually low, check the electronic expansion valve and the pipe sensors.

How to fix6

1. Fully open the service valves if they were partly closed.
2. Remake the leaking flare, or replace a faulty nut or service valve.
3. Repair or replace a leaking evaporator or condenser coil.
4. Only after the leak is fixed: evacuate the system with a vacuum pump and recharge by weight to the nameplate (licensed technician).
5. Replace the expansion valve or sensor if it, not the charge, is the cause.
6. Run the unit for a long period and confirm cooling, pressures and no returning code.

Most cases are a joint leak plus recharge; the top of the range covers a coil or expansion valve leak, and a full coil replacement can go beyond it.

Prices are rough estimates including the part and the technician’s fee, and vary with brand, model and part source.
Prices last updated: September 2026

Frequently asked questions