U8
Gree Split AC
Severity: ModerateWhat Does This Error Mean?
U8 means the sensor monitoring the exhaust temperature at the compressor discharge line has a fault. This sensor protects the compressor from overheating. A loose connector or damaged sensor wire is often all that is wrong.
Affected Models
- Gree FAIRY Series
- Gree LOMO Series
- Gree U-MATCH Series
- Gree PULAR Series
- Gree Inverter Split System
Common Causes
- Sensor wire damaged — pinched, corroded, or broken during installation or service
- Sensor probe has become dislodged from its mounting clip on the discharge pipe
- Connector between the sensor and the outdoor PCB is loose or corroded
- Sensor thermistor has failed and reads out of range
- High vibration over time worked the sensor connection loose
How to Fix It
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Turn off the AC and switch off the outdoor unit circuit breaker.
The outdoor unit must be fully de-energised before inspecting any components.
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Visually inspect the sensor wire running along the compressor discharge pipe.
Look for obvious damage, kinks, or pinch points. The discharge pipe is the hot copper pipe leaving the compressor.
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Check that the sensor probe clip is firmly attached to the discharge pipe.
The probe must be in good thermal contact with the pipe to give accurate readings.
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Trace the sensor wire to its connector on the outdoor PCB and confirm it is fully seated.
Vibration can gradually work a connector partially out — re-seating it often resolves U8.
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If the sensor wire and connector look fine, call a technician to test sensor resistance.
A multimeter test confirms whether the sensor itself has failed and needs replacement.
When to Call a Professional
Call a technician if the sensor connector looks secure but U8 persists. They will test the sensor resistance to confirm if it has failed. Sensor replacement is an inexpensive and quick repair.
Frequently Asked Questions
Why is the exhaust temperature sensor important in a Gree AC?
The compressor discharge pipe carries very hot, high-pressure refrigerant gas. The sensor monitors this temperature to protect the compressor from overheating. If this sensor fails, the unit shuts down as a safety measure.
Can I check the Gree U8 sensor myself?
You can visually inspect the sensor wire and connector — that requires no tools. Testing the sensor resistance requires a multimeter and knowledge of the expected resistance values for your model. Leave electrical testing to a qualified technician.
How much does a Gree exhaust sensor replacement cost?
Sensor replacement is one of the more affordable AC repairs. The sensor itself is inexpensive, and installation takes a technician less than an hour. Total cost is typically a service call fee plus a small parts charge.