ErrorCodeDoctor
LG · Air Conditioner
LG Air Conditioner CH90 error code
Difficulty: Hard
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Cost: $0–$200
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Duration: 5m
The CH90 and CH91 errors appear on LG air conditioners and are most commonly triggered during the test run phase after a new installation or relocation. They act as a protective measure to prevent the unit from running when something is not set up correctly. On some models this code may appear as F4. If the error appeared during normal use rather than after installation it may have been caused by a temporary power issue and a reset will often clear it. A persistent error after resetting requires a technician.
Common causes
- Piping connections between indoor and outdoor units are incorrect or incomplete after installation
- Unit was relocated and piping was not reconnected correctly
- Unstable power supply triggering a false error during operation
- Fault detected in the refrigerant circuit during the test run
How to fix it
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1
If the error appeared after installation or relocation contact the installation technician immediately
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2
Ask them to check all piping connections between the indoor and outdoor units
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3
Their contact details are usually on a business card left during installation or on a sticker on the unit
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4
If the error appeared during normal use unplug the power cord or turn off the circuit breaker and wait 5 minutes
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5
Restore power and check if the error has cleared
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6
If CH90, CH91, or F4 keeps returning after a power cycle contact a technician for inspection