In brief

Fault code F6 on Gree sapphire service manual 18mbh and 24mbh models a means: Fault code F6 indicates a pipe temperature sensor anomaly on the outdoor unit (ODU) detection circuit, causing compressor frequency limitation or reduction. The system detects an AD value out of range for 5 consecutive seconds. Most common cause: The main cause is a pipe temperature sensor (ODU) value that continuously exceeds the upper or lower limits for 5 seconds. This can be due to poor contact between the sensor and the main PCB terminal, sensor failure, or a detection circuit anomaly. First action: Inspect the contact between the pipe temperature sensor and the interface terminal on the main PCB.. Call a registered engineer if the fault returns after basic checks or involves refrigerant work (F-Gas registered engineer required).

According to Gree service documentation, fault code F6 triggers when the sampled AD value of the pipe temperature sensor exceeds both upper and lower limits for 5 consecutive seconds.

F6 • Gree • sapphire service manual 18mbh and 24mbh models a

Gree Fault Code F6: Causes, Diagnosis and Solution

Fault code F6 indicates a pipe temperature sensor anomaly on the outdoor unit (ODU) detection circuit, causing compressor frequency limitation or reduction. The system detects an AD value out of range for 5 consecutive seconds.

Source: Gree documentation (service manual – per product reference) · Updated on 8 June 2026

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What does fault code F6 on Gree mean?

The main cause is a pipe temperature sensor (ODU) value that continuously exceeds the upper or lower limits for 5 seconds. This can be due to poor contact between the sensor and the main PCB terminal, sensor failure, or a detection circuit anomaly.

Symptômes

Fault code F6 displayed on the outdoor unit main PCB LED screen.
Reduced compressor operating frequency.
All other loads operate normally.
Compressor cannot reach its rated frequency.

Diagnostic

1. Check Connections

Inspect the contact between the pipe temperature sensor and the interface terminal on the main PCB.
Check for corrosion or looseness on the connection.

2. Measure Sensor Resistance

Disconnect the sensor and measure its resistance with a multimeter.
Compare the measured value with the temperature/resistance relationship given in Appendix 1 of the manual.

3. Check Detection Circuit

Verify the integrity of the temperature detection circuit on the main PCB.
Confirm that the sampled AD value remains within specified limits.

How to reset fault code F6 on Gree?

If poor contact is identified, clean and tighten the connection between the sensor and the main PCB. If the sensor shows abnormal resistance compared to Appendix 1 specifications, replace the pipe temperature sensor. If the fault persists after replacement, replace the main PCB.

When should you call an F-Gas engineer?

This code appears during a malfunction of the temperature sensor located on the outdoor unit (ODU) detection circuit. It manifests as an automatic reduction in compressor frequency to protect the system, indicating that the temperature value read by the sensor is out of range.

Affected models

Sapphire Service Manual 18MBH and 24MBH
Flexx Eco Service Manual A
Flexx Service Manual AC BH
High Static Slim Duct Service Manual B
Universal Floor Ceiling Service Manual B
All Match Floor Ceiling R32 Service Manual 9K and 24K

Field context

Technical source data

Fault code F6 signals a pipe temperature sensor error (ODU) when the sampled AD value exceeds both upper and lower limits for 5 consecutive seconds via the detection circuit (Extract 1, Extract 2). This anomaly causes compressor frequency limitation or reduction, although all other loads operate normally (Extract 3, Extract 4). Identified causes include poor contact between the sensor and the main PCB terminal, sensor failure, or a detection circuit anomaly (Extract 1, Extract 2). Diagnosis requires checking sensor resistance by referring to Appendix 1 of the manual to correlate temperature and resistance, before concluding a circuit fault if sensor replacement is ineffective (Extract 1, Extract 2).

Sources: flexx eco service manual a — flexx-eco-service-manual-a.pdf (p. 42) · flexx service manual ac bh — flexx-service-manual-ac-bh.pdf (p. 34) · high static slim duct service manual b — high-static-slim-duct-service-manual-b.pdf (p. 33)

Questions fréquentes

What is the exact trigger criterion for fault code F6?

Fault code F6 is triggered when the system samples the AD value of the pipe temperature sensor (ODU) and detects that this value simultaneously exceeds both the upper and lower limits for a continuous duration of 5 seconds. This judgment is made via the temperature detection circuit on the outdoor unit main PCB.

How do I diagnose if the temperature sensor is faulty?

To diagnose a sensor fault, first check the condition of the connection between the sensor and the main PCB terminal. If the contact is good, measure the sensor resistance and compare it with the specifications in Appendix 1 of the service manual. If the resistance is abnormal for the ambient temperature, the sensor must be replaced.

What is the operational consequence of fault code F6 on the compressor?

When fault code F6 is active, the system detects a temperature anomaly on the detection circuit. In response, the compressor operating frequency is automatically reduced or limited. However, the system maintains normal operation of all other loads, only reducing cooling or heating capacity via the compressor.

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