In brief
Fault code H3 on Gree livo gen4 service manual 9mbh 24mbh a means: Fault code H3 indicates compressor overload protection. It triggers when the OVC-COMP interface on the main PCB is open for more than 3 seconds, or when overheating is detected by the protection switch. Most common cause: The main cause is a faulty or loose connection of the OVC-COMP terminal on the main PCB, causing an open circuit. Other causes include a damaged main PCB, abnormal compressor, dirty heat exchanger, or system blockage. First action: Visually inspect the OVC-COMP terminal on the outdoor unit main PCB for looseness.. Call a registered engineer if the fault returns after basic checks or involves refrigerant work (F-Gas registered engineer required).
According to the Gree service manual, the normal resistance of the OVC-COMP terminal should be less than 1 ohm.
H3 • Gree • livo gen4 service manual 9mbh 24mbh a
Gree fault code H3: causes, diagnosis and solution
Fault code H3 indicates compressor overload protection. It triggers when the OVC-COMP interface on the main PCB is open for more than 3 seconds, or when overheating is detected by the protection switch.
Source: Gree documentation (service manual – according to product reference)
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What does fault code H3 on Gree mean?
Fault code H3 indicates compressor overload protection. It triggers when the OVC-COMP interface on the main PCB is open for more than 3 seconds, or when overheating is detected by the protection switch.
The main cause is a faulty or loose connection of the OVC-COMP terminal on the main PCB, causing an open circuit. Other causes include a damaged main PCB, abnormal compressor, dirty heat exchanger, or system blockage.
Symptômes
- Display of code H3 on the outdoor unit (ODU) main PCB, the wired controller, and the indoor unit (IDU) receiver PCB.
- Compressor stops during cooling or dehumidification mode, while the indoor fan continues to run.
- Complete unit shutdown during heating mode.
- Compressor can only restart if the protection trip counter exceeds 6 times (requires a full power cut).
- Specific flashing LED indicators on indoor and outdoor units depending on the model.
Diagnostic
1. Check OVC-COMP connection
- Visually inspect the OVC-COMP terminal on the outdoor unit main PCB for looseness.
- Measure the resistance of the OVC-COMP terminal; the value should be less than 1 ohm under normal conditions.
2. Analyse secondary causes
- Check if the heat exchanger is dirty or if air inlets/outlets are blocked.
- Examine fan operation (speed, abnormal noise) and compressor condition (noise, refrigerant leak).
How to reset fault code H3 on Gree?
If the OVC-COMP terminal is loose, tighten it and check continuity. If the connection is correct but the error persists, replace the outdoor unit main PCB. In cases of overheating, clean the heat exchanger, check for refrigerant leaks, and ensure the system is not blocked by ice or grease.
When should you call an F-Gas engineer?
This code appears during cooling, dehumidification, or heating operations. In cooling, the compressor stops while the indoor fan continues to run. In heating, the entire unit stops. The engineer should first check the continuity of the OVC-COMP terminal.
Affected models
- Gree Livo Gen4 (9MBH, 24MBH)
- Gree Flexx Eco
- Gree Flexx Ultra R32
- Gree High Static Slim Duct
- Gree Universal Floor Ceiling
- Gree PTAC II R32
Field context
This code appears during cooling, dehumidification, or heating operations. In cooling, the compressor stops while the indoor fan continues to run. In heating, the entire unit stops. The engineer should first check the continuity of the OVC-COMP terminal.
Technical source data
Fault code H3 signals compressor overload protection. The trip occurs when the OVC-COMP interface on the outdoor unit main PCB is open (broken circuit) for more than 3 seconds (Extracts 2, 3). In case of overheating, the protection switch activates, stopping the compressor; if this activation exceeds 6 times, a restart requires a power cut and re-energisation (Extract 1). The normal resistance of the OVC-COMP terminal should be less than 1 ohm (Extracts 4, 5, 7). Causes include a loose connection, damaged main PCB, abnormal compressor, dirty heat exchanger, system blockage (ice, grease), or refrigerant leak (Extracts 6, 7).
Sources: multi plus ultra service parts catalog d — multi-plus-ultra-service-parts-catalog-d.pdf (p. 20) · flexx eco service manual a — flexx-eco-service-manual-a.pdf (p. 43) · flexx ultra r32 service manual a — flexx-ultra-r32-service-manual-a.pdf (p. 43)
Questions fréquentes
What does code H3 mean on a Gree unit?
Code H3 indicates compressor overload protection. The system detects an open circuit on the OVC-COMP terminal on the main PCB for more than 3 seconds or activation of the overload switch. This can be due to a loose connection, faulty PCB, abnormal compressor, dirty heat exchanger, or refrigerant leak causing overheating.
How do I diagnose the cause of a code H3?
Start by checking the OVC-COMP terminal connection on the outdoor unit main PCB. The resistance should be less than 1 ohm. If the connection is correct but the error persists, replace the main PCB. If the problem is related to overheating, clean the heat exchanger, check for refrigerant leaks, and ensure the system is not blocked by ice or grease.
How do I reset code H3 after repeated overload?
If the compressor protection switch has activated more than 6 times, a simple reset will not suffice. You must completely cut the power supply to the unit, then restore power to allow the compressor to restart and reset the protection counter.
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