System; U0-00" - Refrigerant Shortage; U2-00" - Power Supply Abnormality Or Instantaneous Power Failure - Daikin 2MXM50M Service Manual

ESIE16-02B | Part 2. Troubleshooting

2.2.3. System

2.2.3.1. "U0-00" – Refrigerant shortage
Trigger
Refrigerant shortage detected.
Possible cause
Faulty air thermistor.
Faulty discharge thermistor.
Faulty outdoor heat exchanger thermistor.
Stop valve is closed.
Refrigerant shortage.
Humidity in refrigerant (ice formation in
expansion valve).
Non condensables in refrigerant.
Faulty compressor.
Faulty expansion valve.
More info:
Check procedures
"Refrigerant thermistors" on page 56
"Compressor" on page 47
"Electronic expansion valve" on page 49
"Error codes" on page 111
2.2.3.2. "U2-00" – Power supply abnormality or instantaneous power failure
Trigger
There is no zero-cross detected in
approximately 10 seconds (indoor unit
PCB).
Abnormal voltage drop (< 150-180 V) is
detected by the DC voltage detection cir-
cuit.
Abnormal voltage rise is detected by the
over-voltage detection circuit.
Page 38
RA R32 Split & multi split M-Series
Effect
Unit will stop operating.
Check
Check air thermistor.
Check discharge thermistor.
Check outdoor heat exchanger thermistor.
Check stop valve.
Check for refrigerant shortage. Refer to
the nameplate for the correct charge.
Check for humidity in the refrigerant.
Check for non condensables in refriger-
ant.
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 the correct charge.
Check the expansion valve.
Replacing procedures
"Replacing compressor" on page 76
"Replacing expansion valve body" on page 81
"Replacing expansion valve motor" on page 82
Effect
Unit will stop operating.
Unit will stop operating.
Unit will stop operating.
2.2. Error based troubleshooting
Reset
Automatic reset.
Power reset via outdoor unit.
Corrective action
Replace air thermistor when required.
Replace discharge thermistor when
required.
Replace outdoor heat exchanger thermis-
tor when required.
Open stop valve when required.
Charge the correct refrigerant amount
when required.
In case of suspicion of humidity, recover,
vacuum and recharge with virgin refriger-
ant.
In case of suspicion of non condensables,
recover, vacuum and recharge with virgin
refrigerant.
Replace compressor when required.
Investigate reason of breakdown.
Replace expansion valve when required.
Fix possible leak.
Replace the expansion valve body or
motor when required.
Reset
Power reset via outdoor unit.
Automatic restart after compressor
stand-by of 3 minutes.
Automatic restart after compressor
stand-by of 3 minutes.
4/04/17 | Version 1.1