Service manual
53
Error code Title and display conditions Possible Cause Diagnosis and action
P1/P2/L5/LD Indoor unit temperature thermistor failure
* The thermistors subject to failure can be
checked in “Request code: 567” in “Running
information
<DHW/Heating/Cooling/LP/FS/OS>
Error code displayed when thermistor is at open
or short (see table).
Exceptions
Error code will not be displayed for TH2; During
defrost and for 10 mins after defrost operation.
Error code
Thermistor
Open detection Short detection
Symbol Name
P1 TH1A/TH1B Room temperature thermistor -39ºC or below 88.5ºC or above
P2 TH2 Liquid temperature thermistor -39ºC or below 88.5ºC or above
L5
THW1 Flow water temperature thermistor -39ºC or below 88.5ºC or above
THW2 Return water temperature thermistor -39ºC or below 88.5ºC or above
THW5 Tank water temperature thermistor -39ºC or below 88.5ºC or above
THW6
Zone 1 fl ow water temperature thermistor
-39ºC or below 88.5ºC or above
THW7
Zone 1 return water temperature thermistor
-39ºC or below 88.5ºC or above
THW8
Zone 2 fl ow water temperature thermistor
-39ºC or below 88.5ºC or above
THW9
Zone 2 return water temperature thermistor
-39ºC or below 88.5ºC or above
LD
THWB1
Boiler flow water temperature thermistor
-40ºC or below 140ºC or above
THWB2
Boiler return water temperature thermistor
-40ºC or below 140ºC or above
1. Connector/terminal wire has become
detached or loose wiring.
1. Visually check the terminals and connec-
tions and reattachas appropriate.
2. Thermistor fault 2. Check resistance of thermistor against ta-
ble in section 10-6.
Compare FTC4 detected temperature to
hand held detector.
3. FTC4 board failure 3. Replace board.
4. The thermistor on the wireless remote
controller or the main remote control-
ler may be defective. (when Room
temp. is chosen for the Heating op-
eration and when Main Controller or
Room RC 1-8 is chosen for the Room
Sensor setting in the Initial setting)
4. Replace wireless remote controller or main
remote controller
5. Incorrect setting of the Dip switch(es) 5. Check the Dip switch setting(s).
L6 Circulation water freeze protection
<DHW/Heating/Cooling/LP/FS/OS>
Error code displayed when THW1 detects a
temp. ≤ 1ºC for 10 consecutive seconds or
THW2 detects a temp. ≤ 3ºC for 10 consecutive
seconds.
Exception
Error code will not be displayed if;
FS function is disabled,
For 10 mins after water circulation pump1 is
switched on.
1. Insuffi cient system head 1. Refer to table in section 10-6. to determine
if system pump meets requirements.
If more head required either add an pump
of the same size or replace existing pump
with capacity model.
See 11. DISASSEMBLY PROCEDURE for
how to replace pump.
2. Reduced fl ow in primary water circuit.
Due to 1 or more of the following;
Faulty pump, insufficient air purge,
blockedstrainer, leak in water circuit.
2. Check circulation pump (See 10-6. for how
to check).
Open purge valve to remove trapped air.
Check the strainer for blockages.
Check the primary water circuit for leaks.
Check that the flow amount is within the
recommended range.
3. Valve operation fault 3. Check valves on primary water circuit are
installed level.
4. 2-way valve (fi eld supply) actuator fault 4. Electrically test to determine fault.
5. 3-way valve actuator fault 5. 1) Electrically test to determine fault.
2) Operate 3-way valve manually using the
main remote controller. (Refer to <Manu-
al operation> in 9.2).
3) Replace 3-way valve coil.
4) Replace 3-way valve. (Refer to Procedure
6 in “11. DISASSEMBLY PROCEDURE.”
6. THW1 has become detached from its
holder.
6. Visually inspect location and reattach as
necessary.
7. THW1 or THW2 fault 7. Check resistance of thermistor against table
in section 10-6.
Compare FTC4 detected temperature to
hand held detector.
8. FTC4 board failure 8. Replace board.
OCH532A