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Monobloc Outdoor Unit Installation Manual
14.0 Troubleshooting
Fault Symptoms:
Symptom
Possible Cause
Corrective Action
Room is not heated or
cooled. Water is not hot
enough.
Incorrect remote controller setting
Check remote controller operation and temperature setting
Incorrect Parameter setting
Check Parameter setting with the Parameter table.
Backup heater disconnected
Check backup heater installation and set up
Insufficient capacity
Check selection of equipment.
Sensor defect
Check whether temperature sensor is installed at the normal position.
Nothing is displayed on
the remote controller.
Power is not supplied.
Check power supply wiring.
Incorrect setting
Check the setting with the Parameter table.
Flow rate switch is
activated.
Air trapped in the pump
Release air completely according to the procedure.
Low hydraulic pressure
Set hydraulic pressure considering pipe height, and replenish water until
manometer shows a value of set hydraulic pressure or more.
Strainer is clogged.
Clean the strainer.
Large resistance on the heating
circuit side
Install larger diameter water pipe work or adopt a bypass valve.
Malfunction of motorized 3-way valve
for hot water supply
Check wiring and parts.
Hot water leaks from
pressure relief valve.
Excessive hydraulic pressure
Set hydraulic pressure considering pipe height, and replenish water until
manometer shows a value of set hydraulic pressure or more.
Insufficient capacity of expansion
tank
Check expansion tank capacity compared to total water amount. If it is
insufficient, install another expansion tank.
Expansion tank failure
Check the air pressure in expansion tank.
Replace expansion tank
Alarm Listing
Check Code
Diagnostic functional operation
Determination and action
Alarm [P344]
Curr
ent Alarm [P346] to [P349]
Past Alarm [P350] to [P354]
Operational Cause
Unit Status
Automatic
Reset
-
1
EWT sensor failure
Continue
X
Automatic reset when the sensor returns within the correct range.
1. Check EWT sensor (EWT)
2. Check NHC board
-
2
LWT sensor failure
Stop
X
Automatic reset when the sensor returns within the correct range.
1. Check LWT sensor (LWT)
2. Check NHC board
-
3
Refrigerant Temperature (TR) sensor
failure
Compressor stop
X
Automatic reset when the sensor returns within the correct range.
1. Check TR sensor (TR)
2. Check NHC board
-
4
OAT sensor failure
Continue
X
Automatic reset when the sensor returns within the correct range.
1. Check additional OAT sensor (OAT)
2. Check NHC board
-
5
DHW_TT sensor failure
DHW failed
X
Automatic reset when the sensor returns within the correct range.
1. Check DHW sensor (DHW)
2. Check NHC board
-
6
CHWSTEMP sensor failure
X
Automatic reset when the sensor returns within the correct range.
1. Check CHWSTEMP sensor (CHWSTEMP)
2. Check NHC board
-
7
IAT sensor failure
Continue
X
Automatic reset when the sensor returns within the correct range.
1. Check IAT sensor (IAT)
2. Check NHC board
-
8
RC indoor temperature failure
Continue
X
Automatic reset when the sensor returns within the correct range.
1. Check RC indoor temperature sensor
2. Check NHC board
