U2
Gree Split AC
Severity: ModerateWhat Does This Error Mean?
U2 means the system detected that the compressor wiring phase order is reversed. A reversed phase would make the compressor run backwards, causing immediate damage. This is almost always an installation wiring error — a technician must swap two compressor wires.
Affected Models
- Gree FAIRY Series
- Gree LOMO Series
- Gree U-MATCH Series
- Gree PULAR Series
- Gree Inverter Split System
Common Causes
- Compressor three-phase power wires connected in wrong sequence during installation
- Wires disturbed and reconnected incorrectly during a service visit
- Outdoor PCB replaced with wires reconnected in wrong order
- Wiring labelling faded or missing, leading to incorrect reconnection
- Drive board fault causing incorrect phase detection (rare)
How to Fix It
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Turn off the AC and switch off the outdoor unit breaker immediately.
The unit will not run the compressor with U2, but power should still be removed for safety.
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Note when U2 first appeared — was it after installation or after a recent service?
If U2 appeared from day one, the installer connected the compressor wires in the wrong order.
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Contact the installer or a Gree-certified technician and tell them you have a U2 error.
They will know immediately that this is a phase order issue and can fix it quickly.
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The technician will swap two of the three compressor power wires to reverse the phase order.
This is a quick fix — the job itself takes minutes once the unit is safely powered down.
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After the fix, restart the unit and confirm U2 has cleared and the unit runs normally.
The compressor should now spin in the correct direction and the unit should cool or heat normally.
When to Call a Professional
Call the installer or a technician immediately. Correcting phase order requires access to the outdoor unit electrical connections. Do not attempt to run the unit with U2 showing — a reversed compressor destroys itself within seconds.
Frequently Asked Questions
Why does my brand new Gree AC show U2?
If U2 appears on a brand new installation, the installer connected the compressor wires in the wrong order. This is a pure wiring error — the unit itself is not faulty. Call the installer to come back and correct the wiring.
Can U2 damage my Gree compressor if I ignore it?
The unit will not start the compressor while U2 is active — it is a protection mechanism. However, if the protection were bypassed or not triggered, running a reversed compressor causes rapid mechanical damage. Do not ignore U2.
Is fixing U2 covered under Gree warranty?
If the unit is brand new and U2 is an installation error, the installer should fix it at no cost. If U2 appeared after a Gree-authorised service, that service should correct it for free. Installation errors by non-authorised installers may not be covered under the unit warranty.