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Error code reference

LG Air Conditioner Error Code E552

Compressor down due to low discharge pressure.

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What the E552 error code actually means

Your LG air conditioner has shut itself off because the pressure inside the refrigerant system dropped too low, which can damage the compressor if it keeps running. This is most often caused by a refrigerant leak, meaning the system does not have enough of the cooling fluid it needs to operate properly. A certified HVAC technician will need to inspect and likely repair the refrigerant circuit before the unit can run safely again.

Diagnostic procedure

The full E552 procedure

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1
Confirm the fault
Power cycle the unit: switch off the breaker for 60 seconds, then restore power. If the code returns, the fault is persistent and the procedure below isolates the cause.
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Most common causes of E552

Ranked by how often they cause this code
  1. 1Low refrigerant charge due to a leak
  2. 2Faulty or clogged expansion valve
  3. 3Defective discharge pressure sensor
  4. 4Blocked or kinked liquid line
  5. 5Compressor mechanical failure

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Questions people ask about E552

What does E552 mean on a LG air_conditioner?
The E552 code means the compressor has shut down because the discharge pressure in the refrigerant circuit fell below a safe operating threshold. This is a protective fault designed to prevent compressor damage. It most commonly points to a low refrigerant charge, a refrigerant leak, or a problem with the refrigerant metering components. A certified HVAC technician is needed to properly diagnose and repair the underlying issue.
Is it safe to keep running my LG air conditioner with the E552 error?
No, you should not continue operating the unit while the E552 fault is active. The system has already shut down the compressor as a protective measure, and forcing the unit to run could cause permanent compressor damage. Leave the unit off until a technician has identified and corrected the underlying cause of the low discharge pressure.
How much does it cost to repair an LG air conditioner with the E552 error?
Repair costs vary depending on the root cause. A refrigerant leak repair and recharge can range from $200 to $700 or more depending on the refrigerant type and leak location. Replacing an expansion valve may cost between $150 and $400 in parts and labor. If the compressor itself has failed, replacement costs can range from $600 to over $1,500, making unit replacement worth considering for older systems.
Can I fix the E552 error on my LG air conditioner myself?
Most causes of the E552 error involve the refrigerant circuit, which requires EPA 608 certification to legally service. Homeowners should not attempt to add refrigerant or repair refrigerant lines themselves. You can visually inspect the unit for obvious issues like ice buildup or blocked airflow, but the core diagnosis and repair must be handled by a licensed HVAC technician.
Will resetting my LG air conditioner clear the E552 error?
A reset may temporarily clear the fault code and allow the unit to restart, but the error will return if the underlying problem has not been fixed. If the cause is a refrigerant leak or component failure, the compressor will simply fault again once pressure drops to the trigger threshold. A reset is not a substitute for proper diagnosis and repair.

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