U5
Gree Split AC
Severity: ModerateWhat Does This Error Mean?
U5 means the circuit that measures AC current on the outdoor PCB is not working correctly. The board cannot safely monitor power consumption without this circuit. This is a board-level fault that needs a technician.
Affected Models
- Gree FAIRY Series
- Gree LOMO Series
- Gree U-MATCH Series
- Gree PULAR Series
- Gree Inverter Split System
Common Causes
- Current transformer or current sensing component on the outdoor PCB has failed
- Wiring to the current sensing circuit is broken or disconnected
- Moisture or corrosion damaged the current monitoring circuit on the PCB
- Power surge damaged the sensor circuit components
- Outdoor PCB has aged and the current sensing circuit has drifted out of spec
How to Fix It
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Turn off the AC and switch off the outdoor unit circuit breaker.
U5 means the board cannot monitor current safely — the unit should not be operated.
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Check the outdoor unit for obvious signs of water ingress or corrosion.
Moisture damage to the outdoor PCB is a common root cause of current circuit faults.
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Try a full power cycle — off for 15 minutes, then restart.
A temporary circuit glitch from a voltage event can sometimes be cleared by a full power cycle.
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If U5 persists after a power cycle, call a Gree-certified technician.
They will test the current sensing circuit and determine if the PCB needs replacing.
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Ask the technician to check the outdoor unit enclosure seal while the unit is open.
If moisture caused U5, resealing the outdoor unit helps prevent the same fault on the replacement board.
When to Call a Professional
Call a technician to diagnose U5 — this is a PCB-level fault with no DIY fix. The current sensing circuit is integrated into the outdoor main board. In most cases the entire outdoor PCB needs to be replaced.
Frequently Asked Questions
What does the AC current circuit do in a Gree outdoor unit?
The AC current sensing circuit monitors how much current the outdoor unit is drawing from the mains. This data is used for efficiency control, protection, and fault detection. Without it, the board cannot safely regulate the unit.
Can U5 be caused by a faulty installation?
In rare cases, a damaged wire during installation could affect the current sensing circuit. However, U5 is more commonly caused by component failure on an existing installation. If U5 appeared on a brand new installation, the installer should investigate.
Is U5 covered under Gree warranty?
If the unit is within the warranty period and the fault is a manufacturing defect, yes. If it was caused by a power surge or installation damage, coverage depends on your specific warranty terms. Contact your Gree dealer with the error code and purchase date.