F4
Gree Split AC
Severity: ModerateWhat Does This Error Mean?
F4 means the sensor monitoring the outdoor discharge pipe temperature has a fault. This sensor is important for protecting the compressor from overheating. A technician will need to inspect and replace the sensor or wiring.
Affected Models
- Gree FAIRY Series
- Gree LOMO Series
- Gree U-MATCH Series
- Gree PULAR Series
- Gree Inverter Split System
Common Causes
- Sensor wire corroded or broken inside the outdoor unit
- Sensor probe damaged by high heat at the discharge pipe location
- Connector at the outdoor PCB terminal loose or oxidised
- Sensor resistance out of specification due to age
- Outdoor PCB port damaged or corroded
How to Fix It
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Switch the AC off at the circuit breaker and wait 5 minutes.
A power cycle can sometimes clear a transient sensor fault caused by a temporary connection issue.
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Restart the unit and observe whether F4 appears immediately or after a few minutes of operation.
Immediate errors typically indicate an open circuit. Delayed errors can point to a sensor that fails only when the discharge pipe heats up.
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If F4 returns, do not continue running the unit — the discharge temperature safety sensor is critical for compressor protection.
Without this sensor working correctly, the AC cannot detect dangerous discharge temperatures in time to prevent compressor damage.
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Call a technician and mention code F4 — they will bring the correct sensor type for your unit.
The discharge pipe sensor is usually a clip-on NTC thermistor. Technicians often carry common Gree sensor types in their service kit.
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Ask the technician to check both the sensor probe and the PCB connector while the unit is open.
Replacing only the sensor while missing a corroded connector will result in F4 returning within a short time.
When to Call a Professional
F4 requires a technician to open the outdoor unit and test the sensor with a multimeter. The outdoor unit contains high-voltage components — do not open it yourself. Discharge pipe sensors are inexpensive, and replacement is usually straightforward.
Frequently Asked Questions
What is the discharge pipe on a Gree AC?
The discharge pipe is the hot gas line leaving the top of the compressor. It carries high-pressure, high-temperature refrigerant vapour to the condenser coil. The F4 sensor clips onto this pipe to monitor its temperature as a safety check.
Can the AC run without the F4 sensor working?
Most Gree models will shut down or limit operation when the F4 sensor fails. The discharge pipe sensor is a critical safety input — the system cannot protect the compressor without it. Repair it as soon as possible.
How is F4 different from E4?
F4 means the sensor itself has a fault — an open or short circuit in the sensor or its wiring. E4 means the sensor is working but reporting a dangerously high temperature reading. F4 is a sensor hardware problem; E4 is an actual temperature alarm.