(Fujitsu) General Australia and New Zealand

Some values in the agent training are generic Fujitsu component test values. Where the ARTG service instruction or model-specific service manual gives a different connector location or value, the model-specific manual takes priority. Use this article as a phone support guide, not as a substitute for the authorised service manual.

• The service instruction shows troubleshooting starts from the error code table and then follows the matching check points.
• For thermistor, fan, drainage, inverter, pressure and 4-way valve faults, do not simply replace a PCB first. Follow the check order: external cause, connection, component test, then PCB.
• If using an older wired remote, use service check / self diagnosis where available and record the code shown.
• If using indoor LEDs, count operation/timer/economy flashes and compare with the service instruction for the exact model.

• Outdoor LEDs display error patterns. Count the LEDs and blink counts before power is cycled.
• Use the outdoor display mode to view operating data such as compressor frequency, upper/lower fan speed, EEV pulse, pressure sensor value, outdoor temperature, discharge temperature, heat exchanger temperature and current where the board supports present-value display.
• Where there is no clear code, use external-cause checks: momentary voltage drop, defective contact, leakage current, harmonic noise near power cables and poor grounding.

• Multimeter with AC volts, DC volts, resistance, continuity, capacitance and diode-test mode.
• Needle-point test leads are preferred for thermistor, EEV and small PCB connectors.
• Diode test is essential for fan motors, IPM and diode bridge. Resistance readings on DC fan motors can be misleading.
• Use a stable DC ground reference where required: fan motor black wire or pressure transducer black wire can be used as common ground when available.

• Communication error between indoor and outdoor.
• Unit powers but does not start outdoor operation.
• Outdoor or indoor PCB suspected, but no component-specific error has been proven.
• Intermittent faults after power interruption, voltage drop, poor earth, harmonic noise or loose terminal repairs.

• At rear of the wall controller, check Y1 to Y3 for 12 V DC. It should not be less than 11.4 V DC.
• For signal test, remove Y2 and test between Y3 and the cable going to indoor unit: fluctuating 7-11/12 V DC pulse.
• Test between Y3 and Y2 terminal: fluctuating 7-11/12 V DC pulse.
• If 12 V supply is not present, suspect the controller board / indoor PCB supply path. If supply is present but no signal, check remote and cable.

• Check connector is not loose, removed or incorrectly connected.
• Check cable is not open, pinched, damaged or shorted to earth.
• Power off: remove connector and check thermistor resistance value.
• Power on: check controller PCB thermistor supply voltage of DC 5.0 V.
• If thermistor is open/shorted, replace thermistor and reset power. If DC 5 V supply is not available, suspect controller PCB after wiring is confirmed.

• Power-off resistance: unplug the thermistor and measure in k-ohms. Compare against actual bulb temperature, not room guesswork.
• Power-on voltage: black meter lead to known DC ground; red lead to each side of the thermistor. One side should be 5 V DC, the other is the return voltage below 5 V.
• Ask for a photo showing meter probes and connector position if recommending a PCB.
• Do not replace PCB for a thermistor code until connector, cable and thermistor resistance have been checked.

• Indoor fan motor errors are associated with fan rotation failure, fan motor winding/open circuit, motor protection due to surrounding temperature rise, power supply PCB failure and fan motor failure.
• The service instruction directs: check fan rotation by hand, check ambient temperature around motor, check indoor fan motor, then replace power supply PCB if earlier checks do not improve the symptom.
• Indoor fan error detection can occur when actual fan frequency stays below one-third of target frequency for more than 56 seconds.

• Outdoor fan motor faults list fan rotation failure, surrounding temperature rise, main PCB failure and outdoor fan motor failure.
• The manual instructs the technician to rotate the fan by hand, check for foreign matter / locked motor, check ambient temperature, check fan motor and then check main PCB output voltage.
• For outdoor fan motor errors, if the outdoor fan motor is abnormal, the service instruction may require replacement of both outdoor fan motor and main PCB depending failure path.

• The service instruction links EEV/strainer checks to low pressure and refrigerant control symptoms.
• The agent training identifies EEV as a DC step motor coil on the valve body, used as the refrigerant metering device.
• Standard Fujitsu product EEV pulse range is generally 0-480 pulses. The ARTG service instruction also lists EEV pulse values in outdoor display mode.
• Check coil condition, corrosion under the coil, that the coil is clipped down and secured firmly to the valve body, and that strainers are not clogged.

• Low pressure error, high pressure switch/sensor error, pressure sensor characteristic fault, or pressure-related protective stop.
• Before condemning a pressure sensor, confirm valves are open, heat exchanger airflow is clear, fans run, filters/coils are not blocked, EEV and strainers are not obstructed, and refrigerant charge/leak history is checked.

• All three windings should have equal resistance, typically approximately 1-2 ohms at 20-25 C.
• Check U-V, V-W and U-W. The absolute value can vary, but balance between the three readings is critical.
• Insulation test from any winding to earth must be greater than 1 M-ohm.
• If compressor is connected to IPM during testing, disconnect harness and test directly at compressor pins where safe/accessible.
• Do not diagnose compressor from an IPM trip alone; test compressor, IPM and bridge separately.

These tests involve high voltage components. Only qualified technicians should perform them. Power-off diode/resistance tests require supply isolated, capacitors discharged and control harnesses removed where required.

• If a diode bridge or IPM reading is shorted/open against expected values, replace the failed module/PCB as applicable.
• If ACTPM is shorted, it may trip the circuit breaker. Check physical damage before replacement.
• If replacing any part mounted to heatsink plate, apply heatpaste correctly. Poor heat transfer can cause repeat failure.
• If the board has protective silicon gel, ensure the probes make solid contact with solder/test points before judging readings.

• The ARTG service instruction identifies 4-way valve fault causes as connector failure, thermistor failure, solenoid coil failure, 4-way valve failure and main PCB failure.
• For these older ARTG/AOTG units, treat the 4-way valve as AC solenoid style unless proven otherwise from the exact PCB/circuit diagram.
• Training notes: AC 4-way valves use electricity throughout heating. DC pulse valves only use power during switching and are used on newer models.

• Drainage error is based on float switch ON for more than 3 minutes.
• Forecast causes: float switch failure, shorted connector/wire, controller PCB failure, drain pump failure and hose clogging.
• Check physical drain path before recommending PCB.

• Defrost start is based on compressor accumulated operation time and outdoor heat exchanger temperature.
• Defrost release occurs when outdoor heat exchanger temperature rises above approx. 10 C or compressor operation time reaches maximum 15 minutes.
• Off-defrost can start after heating operation stops if frost is present and conditions are met.
• During defrost, indoor operation lamp can indicate slow flash pattern depending model. Confirm whether the customer is seeing normal defrost, not a fault.

Based on the readings provided, the next action is [repair/replace part/check installation]. Please attach the meter readings and photos to the job before ordering parts or submitting the warranty claim, as the claim may be reviewed against the service manual and component test evidence.