U4-00" - Transmission Abnormality Between Indoor Unit And Outdoor Unit - Daikin 2MXM50M Service Manual

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