Mitsubishi Electric EHGT17D-YM9ED Service Manual page 47

Error code Title and display conditions
L9 Low primary circuit (Zone2 side) flow rate
detected by flow switch
Note: "3" is displayed in "Request code: 569" in
"Running information".
LC Boiler circulation water temperature overheat
protection
<DHW/Heating/LP/FS/OS>
Error code displayed when THWB1 detects a
temp. ≥80ºC for 10 consecutive seconds
LD Boiler temperature thermistor (THWB1) failure
LE Boiler operation error
<Heating>
Boiler is running and THW6 detects a
temperature <30ºC for consecutive 60 minutes.
LF Flow sensor failure
LH Boiler circulation water freeze protection
LJ DHW operation error (type of external plate HEX)
LL Setting errors of DIP switches on FTC control
board
P1 Indoor temperature thermistor (TH1) failure
P2 Indoor temperature thermistor (TH2) failure
E0/E4 Main remote controller communication failure
(Reception error)
Error code E0 is displayed if main remote control-
ler does not receive any signal from the FTC for
ref. address "0" for 3 minutes.
Error code E4 is displayed if FTC does not receive
any data from the main remote controller for 3
minutes or FTC does not receive any signal from
the main remote controller for 2 minutes.
OCH722A
Possible Cause
1. Insufficient system head
2. Reduced flow in primary water circuit
Due to 1 or more of the following;
Faulty pump, insufficient air purge,
blocked strainer, leak in water circuit
3. Terminal wire has become detached
or loose wiring.
4. Flow switch fault
5. Incorrect setting of the SW3-3 on the
FTC board
6. FTC board failure
1. The set temperature for Boiler is too
high.
2. Flow rate of the heating circuit from the
boiler may be reduced.
Refer to error codes (P1/P2/L5/LD).
1. THW6 has become detached from its
holder.
2. Incorrect wiring between FTC (OUT10)
and the boiler.
3. Boiler fuel has run out or the system is
OFF.
4. Boiler failure
5. FTC board failure
Disconnection or loose connection of flow
sensor
Flow rate of the heating circuit from the boil-
er may be reduced.
1. DHW tank water temp. thermistor
(THW5A/B) has become detached from
its holder.
2. Flow rate of the sanitary circuit may be
reduced.
Incorrect setting of DIP switches.
1. Boiler operation
2. 2-zone temperature control
Refer to error codes (P1/P2/L5/LD).
Refer to error codes (P1/P2/L5/LD).
1. Contact failure with transmission cable
2. Wiring procedure not observed.
(Cable length/cable diameter/number
of main remote controllers)
3. Fault on the FTC board section
controlling Ref. address "0"
4. Fault with the main remote controller
circuit board
5. Electrical noise causes interference
with transmission/reception of data for
main remote controller.
47
Diagnosis and action
1. If more head required either add a pump of
the same size or replace existing pump.
2. Check circulation pump (See "9-6.
Checking Component Parts' Function" 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. Visually check the IN7 terminal and
reattach if necessary.
4. Electrically test to determine fault.
5. Check the SW3-3 setting on the FTC board.
6. Replace board.
1. Check if the set temperature for Boiler for
heating exceeds the restriction. (See the
manual for the thermistors "PAC-TH011HT-E")
2. Check for
• water leakage
• strainer blockage
• water circulation pump function.
1. Visually inspect location and reattach as
necessary.
2. See the manual of the thermistors
"PAC-TH011HT-E".
3. Check the status of the boiler.
4. Check the status of the boiler.
5. Replace board.
Check flow sensor cable for damage or loose con-
nections.
Check for
• water leakage
• strainer blockage
• water circulation pump function.
1. Check for disconnection of DHW tank water
temp. thermistor (THW5A/B).
2. Check for water circulation pump function.
1. For boiler operation, check that DIP SW1-1
is set to ON (With Boiler) and DIP SW2-6 is
set to ON (With Mixing Tank).
2. For 2-zone temperature control, check DIP
SW2-7 on the FTC board is set to ON
(2-zone) and DIP SW2-6 on the FTC board
is set to ON (With Mixing Tank).
1. Check connection cable for damage or
loose connections at the FTC and main
remote controller terminals.
2. Check main remote controller and FTC
common wiring max cable length 500 m.
Only use 2-core cable.
Only connect 1 main remote controller to 1
FTC board.
3. to 5.
If the problem is not solved by the above
measures then:
Turn the power to the unit OFF and then
ON.
If the E4 code is still displayed the FTC and/
or the main remote controller circuit board
should be replaced.