LG mini split error code CH73
AC input instantaneous over-current. Also shown as CH 73, CH73.
- TypeProtection
- SystemPower supply
- Can I fix it?Homeowner checks, then maybe a tech
What CH73 means on a LG
The input current spiked over its limit for an instant.
On this platform, CH73 is a protection: the system stopped or throttled itself to prevent damage; many clear on their own once conditions return to normal.
Common causes
- Low or unstable supply voltage.
- A blocked outdoor coil.
- A failing compressor.
How to fix it yourself
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician.
- If you own a multimeter and are comfortable using it, measure the supply voltage at the outdoor unit's L1 and L2 terminals with the unit running. A 230 V system should read roughly 208 to 253 VAC.
- Look at the outdoor unit: clear leaves, cottonwood fluff, snow or ice from the coil and make sure the fan can spin freely and nothing is stacked against the cabinet.
- Reset the system: switch the breaker (or the outdoor disconnect) off, wait a full five minutes so the boards fully discharge, then switch it back on and restart from the remote.
Switch off power at the breaker before opening either unit. Capacitors in the outdoor unit hold a charge for several minutes after power is cut.
When to call a technician
Technician check if it persists.
Which LG units show CH73
This page applies to LG Art Cool, Standard, Mega and Multi F units. LG's own documentation lists CH73 as "AC input instantaneous over-current", the same definition used across the LG it is built on. If your unit shows a code with a different shape (for example a four-character code, or a plain number), it is from a different table; use the lookup with your exact code.
Where LG shows this code
The indoor display shows CH followed by a number (CH05, CH38). Units without a display blink the indicator lamps in a pattern; the outdoor board LEDs blink the same number. If someone tells you 'CH 5', that is CH05. CH01 to CH12 are indoor-unit faults, CH21 to CH29 are inverter and compressor faults, CH32 to CH38 are refrigerant-side protections, CH40 to CH48 are outdoor sensors, and CH51 to CH73 are outdoor-unit system faults.
Other LG codes
Same part of the system as CH73:
Questions people ask
Can I reset a LG CH73 code myself?
Yes. Turn the system off at the breaker for five minutes, then restart it. If CH73 comes back, the fault is real and needs the checks above.
Is it safe to keep running a LG showing CH73?
Not repeatedly. A protection code means the unit stopped itself to prevent damage, and resetting it over and over can turn a cheap repair into a compressor failure. Reset once, check the basics, and stop if it returns.
Do I need a technician for LG CH73?
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician. Technician check if it persists.
Sources
- LG residential split service manuals (error code tables)
Updated September 2026. Codes and definitions vary by model year. If your manual disagrees with this page, your manual wins. Send a correction.