Daikin D2CND028A1AA Servicing Manual page 42

10 Troubleshooting
ERROR
REASON
CODE
Return
temperature
J6-20
sensor over-
heating
Return tem-
perature is
J6-21 higher than
flow tempera-
ture
Flue tempera-
JJ-64 ture sensor
fault
Supply voltage
U2-01 is below low
limit
Supply voltage
U2-01 is above high
limit
Opentherm RT
U4-65 connection is
defective
CAN-Bus
U4-66
timeout
Remote reset
U4-67
supervision
Blocking during
UA-64 BCC update
process
PCB requires a
UA-65
BCC update
BCC-ID
of internal
UA-66
EEPROM is
inconsistent
Servicing manual
42
ELIMINATION
This can be a blocking error or
lockout error, reset the boiler
if it is lockout. Check return
NTC sensor resistance using
a multimeter connected across
the thermistor's terminal pins,
replace the sensor if it is not as
desired.
Be sure that flow and return
temperature sensor electrical
leads are placed correctly.
Check flow and return tempera-
ture sensors resistances using
a multimeter connected across
the sensor's terminal pins.
Replace defective sensor.
Reset the boiler. If the error
is still present, Check flue
temperature sensor resistance
using a multimeter connected
across the thermistor's terminal
pins, replace the sensor if it is
not as desired. Check sensor
cable connection, replace if
defective.
The appliance is blocked. Sup-
ply voltage must exceed 180
volts for boiler operation. Check
the electrical circuit of the build-
ing, use voltage stabiliser.
Boiler continues operation but
electrical circuit of the building
should be checked and voltage
stabiliser should be used for
smooth operation.
Boiler operates as if Opentherm
room thermostat not connected.
Check the thermostat electri-
cal connections, be sure that
connections are done correctly.
Lastly, check the thermostat,
replace if defective.
Check the connection between
the LAN adapter and the PCB.
Switch off and switch on the
electric supply to the boiler.
This error occurs when BCC is
plugged to the PCB for the very
first time and the process has
not been initialised yet. This
error also occurs is BCC update
is blocked somehow (e.g., elec-
trical interruption). Initialize the
update process again.
Occurs when re-update is
requested but not executed yet.
Re-update the BCC.
Be sure correct BCC is plugged.
ERROR
REASON
CODE
UA-67 BCC is missing
BCC is not
compatible
UA-68
with PCB
(BCC-ID)
BCC is not
compatible
UA-69
with PCB (firm-
ware)
BCC update
UA-70
error
D2CND028A1AA + D2CND028A4AA + D2CND035A1AA +
D2CND035A4AA + D2TND028A4AA + D2TND035A4AA
ELIMINATION
PCB does not operate if the
BCC, which has already over-
written to PCB, is connected
to it. Make sure correct BCC
is plugged to PCB and it is
plugged correctly.
Be sure BCC is plugged correct-
ly. If error is still present, replace
the BCC with a proper one.
Make sure proper BCC is
plugged to the PCB.
Appears if BCC update proce-
dure has not started by user
within the timeout of 5 minutes.
Wall-mounted condensing boiler
ESIE17 - 09 / 2017.11