ESIE16-02B | Part 2. Troubleshooting 2.2. Error based troubleshooting
4/04/17 | Version 1.1 Page 39
RA R32 Split & multi split M-Series
More info:
2.2.3.3. “U4-00” – Transmission abnormality between indoor unit and outdoor unit
Possible cause Check Corrective action
Faulty or disturbance of the power supply
(imbalance > 10%). Power drop. Short cir-
cuit.
Check if the power supply is conform with
regulations. No fluctuations in frequency.
Adjust power supply when required.
Power reset via outdoor unit.
Defective DC voltage detection circuit. Check PCB with DC voltage detection cir-
cuit.
Replace PCB when required.
Defective over-voltage detection circuit. Check PCB with over-voltage detection
circuit.
Replace PCB when required.
Defective PAM control part. Check PAM control part. Replace PAM control part when required.
Faulty compressor. Check compressor.
Check connections and wiring of the com-
pressor.
Check expansion valve (liquid back
issue).
Check the refrigerant charge. Refer to the
nameplate for correct charge.
Replace compressor when required.
Investigate reason of breakdown.
Replace expansion valve when required.
Fix possible leak.
Faulty outdoor fan motor. Check the fan motor.
Check fan motor connections and wiring.
Replace fan motor when required.
Adjust wiring when required.
Momentary drop of voltage. - Wait until compressor restarts.
Momentary power failure. - Wait until compressor restarts.
Faulty outdoor unit main PCB. Check if the HAP LED is blinking in regu-
lar intervals.
Check if the correct spare part is installed.
Check if the outdoor main PCB receives
power.
Restore the power to the outdoor main
PCB.
Replace outdoor main PCB when HAP
LED is not blinking in regular intervals.
Faulty indoor unit main PCB. Check if the HAP LED is blinking in regu-
lar intervals.
Check if the correct spare part is installed.
Check if the indoor main PCB receives
power.
Restore the power to the indoor main
PCB.
Replace indoor main PCB when HAP LED
is not blinking in regular intervals.
Check procedures Replacing procedures
"Compressor" on page 47 "Replacing compressor" on page 76
"Electronic expansion valve" on page 49 "Replacing expansion valve body" on page 81
"Fan motor" on page 51 "Replacing DC fan motor assembly" on page 79
"Main PCB" on page 53 "Replacing main PCB" on page 84
Trigger Effect Reset
Data sent from outdoor unit cannot be
received normally, content of the send
data is abnormal.
Unit will stop operating. Power reset via outdoor unit.
Possible cause Check Corrective action
Faulty or disturbance of the power supply
(imbalance > 10%). Power drop. Short cir-
cuit.
Check if the power supply is conform with
regulations. No fluctuations in frequency.
Adjust power supply when required.
Power reset via outdoor unit.
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