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Toshiba
9-3-4. How to diagnose by error code
Defect mode detected by the water heat exchange
O ... Possible
× .... Not possible
Check
code
Diagnostic functional operation
Determination and action
Number of
abnormalities
for
confirmation
Detailed
item
Operational cause
Backup
present
Automat
ic reset
A01
Pump or flowing quantity error
1) Detected by TC sensor
TC 63°C is detected in the heating or
hot water supply heat pump operation
(except for defrosting).
×
×
1.Almost no or little water flow.
• Not enough vent air
• Dirt clogging in the water piping
system.
• The water piping is too long.
• Installation of buffer tank and
secondary pump
474
2)Detected by flow switch abnormality
When no signal of the flow switch is
showing 2 min after the built-in pump
operation started.
274
3)Detection of chattering abnormality in
the flow switch input
Chattering detection: Detects input
changes (OFF⇔ON) 4 times within
10 seconds during operation.
474
4)Disconnection of the flow switch
connector
When the stopped built-in pump starts
its operation, the flow switch status is
detecting "water flow".
1.Disconnection of the flow switch
connector.
2.Defect of the flow switch.
274
A02
Temperature increase error (heating)
When one of the TWI, TWO and THO
sensors exceeds 70°C.
Heating
O
Hot water
×
O
1.Check the water inlet, water outlet
and heater outlet (TWI, TWO, THO)
sensors.
2.Defect of the backup heater (defect
automatic reset thermostat).
175
A03
Temperature increase error (hot water
supply)
When the TTW sensor exceeds 85°C.
Heating
O
Hot water
×
O
1.Check the hot water cylinder sensor
(TTW).
2. Check the hot water cylinder thermal
cut-out.
176
A04
Antifreeze operation
1)TWO>20°C condition:
2×TC+TWO < -12°C is detected.
2)TWO 20°C condition:
TC+TWO < 4°C is detected.
3)TWI 10°C is detected during
defrosting.
O
×
1.Almost no or little water flow.
• Dirt clogging in the water piping
system.
• The water piping is too long.
2.Check the heater power circuit.
• Power supply voltage, breaker,
power supply connection
3.Set the presence of the backup
heater.
4.Check the water inlet, water outlet
and heat exchange (TWI, TWO, TC)
sensors.
Heating2
Hot water2
Cooling4
77
A05
Piping antifreeze operation
Activating the heater under the condition
of TWO<4orTWI<4orTHO<4 does not
achieve TWO,TWI,THO 5°C after 30
min elapsed.
OO
1.Check the heater power circuit.
• Power supply voltage, breaker,
power supply connection
2.Check the water inlet, water outlet
and heater outlet sensors (TWI,.
TWO, THO).
3.Disconnection of the backup heater.
178
+00A09-002_01EN_SVM_ALL_Air_to_Water.book Page 67 Monday, October 5, 2009 2:09 PM