General Assist Technical Troubleshooting
Outdoor Unit Starts, Stops and Repeats
ARTG45LHTA ducted system
Compressor operates for approximately one minute, stops, then restarts after a delay
High-voltage warning: This procedure includes live testing around approximately 330 V DC. It must only be completed by suitably qualified personnel using correctly rated test equipment and appropriate PPE. DC voltage can remain present after power is isolated.
Reported operating condition: Heating set to 30°C, room temperature approximately 16°C, indoor fan operating continuously, no fault code shown, outdoor compressor and fans run for about one minute, then stop and restart after approximately two minutes.
1. Symptom confirmation
| Check | Confirmed |
|---|---|
| Indoor model is ARTG45LHTA | ☐ |
| Controller is in HEAT at 30°C | ☐ |
| Room temperature is well below setpoint | ☐ |
| No controller fault code | ☐ |
| No outdoor LED fault indication | ☐ |
| Compressor and fans repeatedly cycle approximately every 1–2 minutes | ☐ |
The indoor fan continuing to run does not confirm that the outdoor unit is operating normally. The key issue is why the compressor is being stopped by the outdoor control.
2. Check compressor running current
| 1 | Fit a suitable clamp meter to the compressor supply conductor before starting the unit. |
| 2 | Run the system in heating and observe the compressor current from startup until the compressor stops. |
| 3 | Record the starting current, stable running current and current immediately before shutdown. |
| 4 | Compare the observed current with the expected compressor operating current and inverter behaviour for the model. |
If compressor current is excessive: The compressor may be mechanically or electrically defective. Before replacing the compressor, recheck the outdoor main PCB, inverter/IPM section and capacitor/DC-bus PCB to confirm they have not also been damaged.
3. Check the DC bus at the red plug
Locate the red plug at the front of the outdoor electrical assembly. The plug has:
White wire Black wire
| 1 | Set the multimeter to a DC range suitable for at least 400 V DC. |
| 2 | Measure DC voltage across the white and black wires at the red plug. |
| 3 | Record the DC voltage before the compressor starts. |
| 4 | Continue monitoring the voltage while the compressor is running and immediately before shutdown. |
Expected result: The DC bus should remain around 330 V DC while the compressor operates.
If the DC voltage drops below approximately 330 V when the compressor starts or runs: Suspect the capacitor/DC-bus PCB or its associated supply path. A collapsing DC bus can cause the inverter to stop the compressor without immediately producing a clear fault code.
4. Diagnostic decision guide
| Test result | Likely direction | Next action |
|---|---|---|
| Compressor current rises excessively before shutdown | Possible compressor mechanical or winding fault | Complete compressor winding, insulation and mechanical assessment. Recheck all outdoor PCBs before compressor replacement. |
| DC bus falls below approximately 330 V during compressor operation | Capacitor/DC-bus PCB or rectification supply issue | Inspect capacitor PCB, rectifier, connections and supply voltage under load. |
| Compressor current normal and DC bus stable | Outdoor control, inverter drive, sensor interpretation or protection input | Recheck main PCB, IPM/inverter output, sensor values under operating conditions and all connectors. |
| Voltage or current changes when connectors are moved | Poor plug, terminal or harness connection | Inspect for loose pins, heat damage, corrosion, poor crimping or partially seated plugs. |
5. Additional checks before replacing parts
| Check | Done |
|---|---|
| Outdoor supply voltage remains stable under load | ☐ |
| All outdoor plugs and PCB connectors fully seated | ☐ |
| No heat damage or discolouration on terminals or plugs | ☐ |
| Outdoor thermistors checked at rest and under operating conditions | ☐ |
| Refrigerant pressures and pipe temperatures recorded | ☐ |
| Compressor current recorded from startup to shutdown | ☐ |
| DC bus voltage recorded before and during compressor operation | ☐ |
| Main PCB, inverter/IPM and capacitor PCB visually inspected | ☐ |
6. Information required for escalation
Provide the following readings with any further technical-support escalation:
- Indoor and outdoor model numbers
- Indoor and outdoor serial numbers
- Outdoor supply voltage before and during compressor operation
- Compressor running current and current immediately before shutdown
- DC bus voltage at the red plug before and during compressor operation
- Suction and discharge pressures
- Outdoor thermistor resistance or temperature readings
- Photos of the outdoor main PCB, capacitor PCB and red plug
- Confirmation of which PCB was replaced and its part number
Key diagnostic principle: Do not condemn the compressor or another PCB from the cycling symptom alone. Capture compressor current and DC-bus voltage at the exact moment the outdoor unit stops.
This article is a targeted troubleshooting guide based on the reported ARTG45LHTA operating symptoms. It does not replace the relevant service manual, electrical safety procedures or model-specific component test data.