LG Mini-Split CH38 Error Code: What It Means and How to Fix It

By Dan Mercer · Published October 5, 2026 · Updated October 6, 2026 · Codes covered: CH38, F4 · Sources

Verify in your manual: F4 means CH38 on some LG models but CH90/CH91 on others. LG's guide was written for all models, so check your manual or ask LG.

CH38 on an LG mini-split or ductless air conditioner means the system thinks it's low on refrigerant. It's a protection code, so the unit stops to avoid damage. A reset can clear a one-off false alarm, but a real refrigerant shortage isn't a DIY repair: it needs your installer or a certified HVAC technician.

This 3-minute fix saved 0 homeowners a technician visit this month.

What the CH38 code means

LG's US help article "[LG Air Conditioner] Guide to Error Codes" says: "CH38 / F4 errors indicate that the air conditioner is low on refrigerant (gas). This warning is designed to protect the appliance from potential damage."

LG splits it into two situations:

• Right after installation or a move. "If so, the error likely points to a refrigerant shortage." LG says the piping connection may also need checking, and that you should contact the installation technician.
• During normal use. "The issue may be temporary, caused by unstable power or other electrical factors." Power-cycle the unit first. If CH38 comes back, contact LG.

How CH38 shows up:

• Displays: "CH" and the number appear on the indoor unit's display.
• Wall-mount units without a display: the code shows as LED blinks. LG's guide "How to Check Air Conditioner Error Codes" says the first LED shows the ones digit and the second LED shows the tens digit. For CH38, the second LED blinks 3 times and the first blinks 8 times.
• The ThinQ app: if your unit is connected, LG's Smart Diagnosis in the app can show the error.

About F4: LG says some models show F4 instead of CH38. But LG also says CH90/CH91, which "are typically displayed during the test run phase," may show as F4 on some models. So if your unit shows F4 right after installation, it could be either one. Ask your installer or LG.

Likely causes (most common first)

1. A new install or a recent move. LG says CH38 after installing or relocating usually points to a refrigerant shortage or a piping connection problem.
2. A temporary electrical glitch. During normal use, LG says CH38 can come from unstable power. A power cycle often clears it.
3. A refrigerant problem on an established system. If CH38 keeps coming back on a system that's been running fine for a while, a technician needs to check the charge and look for a leak.
4. A sensor or control fault. LG says that if a code keeps coming back after a reset, it "may indicate an internal circuit or wiring problem."

How to fix it, step by step

You can safely do steps 1–4. Everything after that is for a pro.

1. Write down the code and when it happened. Note whether it showed up right after installation or a move, or during normal use. LG says to leave the power on until you've read the code, then switch it off.
2. Power-cycle the system. LG says: "Unplug the power cord or turn off the circuit breaker, wait for 5 minutes, then restore power." Most US mini-splits are hardwired, so use the breaker. If there's an outdoor disconnect switch, turn that off too.
3. Restart and watch. If CH38 doesn't come back and the unit cools or heats normally, LG says you can keep using it.
4. Check the basics while you wait. These won't fix a refrigerant shortage, but they rule out other problems:
   • Clean the indoor unit's air filter. LG says a dusty filter can trigger its overheating code, CH61.
   • Clear leaves, snow, and stored items from around the outdoor unit. LG says clutter there keeps hot air from escaping.
5. New install? Call the installer. LG says to contact the installation technician and adds: "You can find their contact information on the business card provided during their visit or on the side of the unit."
6. Existing install? Call LG. If the error reappears after a power cycle, contact LG support.
7. Stop resetting it over and over. If CH38 returns, stop using the unit and get it inspected.

Test the part

There's no safe owner test for CH38. Checking refrigerant needs gauges on the sealed system. In the US, that's a job for an EPA Section 608–certified technician. These visual checks are safe and can help the technician.

1. Turn the system off at the remote, then switch off the breaker (and the outdoor disconnect, if there is one).
2. Look at the outdoor unit and the line set (the insulated copper pipes between the units) from a few feet away. Look for crushed or torn insulation, physical damage, or anything that's hit the pipes. Don't touch the fittings or valves.
3. Look at the indoor unit for ice, dripping water, or anything unusual.
4. Take photos of what you see, plus the indoor and outdoor model labels.
5. Stop there. Don't open panels, don't loosen or tighten fittings, and don't add refrigerant.

Safety notes

When to call a pro

Contact your installer, an HVAC technician, or LG if:

• CH38 appears right after installation or a move. Call the installer first.
• CH38 comes back after a 5-minute power cycle.
• You see ice on the indoor unit, damaged line-set insulation, or physical damage outdoors.
• The unit shows F4 and you're not sure whether it means CH38 or a test-run error.
• The system is under warranty. Have any service invoices ready.

LG US support: lg.com/us/support, or 1-800-243-0000 (from LG's US contact page). You can also ask for help from the ThinQ app's Smart Diagnosis.

FAQ

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