U2" - Power Supply Voltage Abnormality; U3-00" - Abnormal Stop Of Underfloor Heating Dry-Out Scheduled Operation; U4" - Defective Indoor-Outdoor Transmission - Daikin EGSQH10S18AA9W Service Manual

ESIE13-03 | Part 2. Troubleshooting
2.39. "U2" – Power supply voltage abnormality
Trigger
Inverter PCB detects an abnormal power
supply (drop or peak).
Possible cause
Power supply is not OK -> imbalance
> 10% (rated power supply: 400 V).
Power supply is not OK -> reverse phase.
Faulty inverter PCB A10P.
2.40. "U3-00" – Abnormal stop of underfloor heating dry-out scheduled
operation
Trigger
Screed dry-out program was interrupted.
No heat source detected.
Possible cause
User interface has been turned off.
Power failure.
2.41. "U4" – Defective indoor-outdoor transmission
Trigger
Hydro PCB detects abnormal transmis-
sion to refrigerant/brine PCB for a certain
time.
Possible cause
Power supply is not OK -> imbalance
> 10% (rated power supply: 400 V).
Wiring between refrigerant/brine PCB
A9P and hydro PCB A1P is not OK.
Faulty refrigerant/brine PCB A9P.
Faulty hydro PCB A1P.
External factor (e.g. electrical noise)
(cause when error is reset after power
reset, and error happens again after
awhile).
13/05/15 | Version 2.0
Ground source heat pump
Effect
Unit will stop operating.
Check
Check power supply for voltage fluctua-
tions (> 10%).
Check power supply.
Check inverter PCB A10P (see
Effect
Unit will stop UFH dry-out schedule.
Check backup heater.
Check
Check user interface.
Check power supply.
Effect
Unit will stop operation.
Check
Check power supply for voltage fluctua-
tions (> 10%).
Check the wiring (refer to the wiring dia-
gram).
Check for source which could cause elec-
trical interference.
2. Error code based troubleshooting
Reset
Via user interface.
Corrective action
Voltage fluctuations should be less than
10%.
Change two phases with each other.
page 75). Replace inverter PCB A10P (see
page 97).
Reset
Via user interface -> only possible in
"installer" level.
Restart screeds dry out program. Refer to
the Installer Reference Guide.
Corrective action
Restart screed dry out program. Refer to
the Installer Reference Guide.
Restart screed dry out program. Refer to
the Installer Reference Guide.
Reset
Auto-reset.
Corrective action
Voltage fluctuations should be less than
10%.
Correct the wiring.
Replace PCB A9P (see
Replace PCB A1P (see
page 96).
page 93).
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