Mitsubishi Electric LGH-50RSDC-E1 User manual

Warning:
Repair work must be performed by the manufacturer, its service
agent or a similarly qualified person in order to avoid hazards.
LOSSNAY
HANDBOOK
MODEL
LGH-50RSDC-E1 1
July 2019 No. U177-B
Nameplate

Contents
1. Safety precautions ....................................................................... 3
2. Names of components ................................................................ 4
3. Specifi cations ............................................................................... 5
4. Outside dimensions ...................................................................... 6
5. Electrical wiring diagram ............................................................. 7
6. Basic circuit diagrams ............................................................... 8-9
7. Fundamentals of operation ................................................... 10-15
8. Troubleshooting .................................................................... 16-22
9. Overhauling procedures ....................................................... 23-27
10. Parts catalog ......................................................................... 28-34

─3 ─
Be sure to read the following precautions thoroughly before the maintenance, and then inspect and repair the
product in a safe manner.
The types and levels of danger that may arise if the product is handled incorrectly are described with the warning
symbols shown below.
Warning
Modification is prohibited
Do not modify the unit.
(Failure to heed this warning may result
in electric shock, fire and/or injury.)
Electric shock
If you must inspect the circuitry while the power is
on, do not touch the live parts.
(Failure to heed this warning may result
in electric shock.)
Check insulation
Upon completing repair work, always measure the
insulation resistance. Verify that it is at least 10 MΩ
(with a 500 V DC insulation resistance tester), and
then turn on the power.
(Inadequate insulation may cause electric
shock.)
Incorrect handling of the product may
result in serious injury or death.
Caution Incorrect handling of the product may result in serious injury
or damage to properties including buildings and equipment.
Proper electric work
Use the electric wires designated for electric work,
and conduct electric work in accordance with the
"Electric Installation Engineering Standard", the
"Indoor Wiring Regulations" and the installation
instructions.
(Improper connection or wiring installation
may result in electric shock and/or fire.)
Replace damaged and/or degraded parts
Be sure to replace the power-supply cord and lead
wires in the event that they are damaged and/or
degraded.
(Failure to heed this warning may result
in electric shock and/or fire.)
Use proper parts and tools
For repair, be sure to use the parts listed in the
service parts list of the applicable model and use the
proper tools.
(Failure to heed this warning may result in
electric shock, fire and/or bodily injury.)
Caution against
electric shock
Prohibited
Be sure to follow
this instruction.
Turn off the power supply
Be sure to shut off the power supply isolator before
disassembling the unit for repair.
(Failure to heed this warning may result
in electric shock.)
Make sure that the product operates properly upon completion of repair. Clean the product and the surrounding
area, and then notify the customer of the completion of repair.
Caution for injury
Do not work at a location where you do not have a
sure footing.
(Failure to heed this caution may result in
a fall.) Prohibited
Request for repair
●Inspect the earth condition, and repair it if it is incomplete. Make sure that a power supply isolator or an
overload protection device is installed, if it is not installed, recommend the dealer to install one.
Be sure to follow
this instruction.
Be sure to follow
this instruction.
Be sure to follow
this instruction.
Be sure to follow
this instruction.
Wear gloves
Wear gloves when servicing.
(Failure to heed this caution may result in
injury to your hands from sharp metal or
other edges.) Be sure to follow
this instruction.
1. Safety precautions

─4 ─
2. Names of components
Air filter
(4 filters)
Lossnay core
Maintenance cover
Control box
Air supply fan
(SA fan)
Damper plate
Air exhaust fan
(EA fan)

─ 5 ─
3. Specifi cations
Model LGH-50RSDC-E1 1
Heat exchange system Air-to-air Total heat exchange (sensible heat + latent heat exchange)
Heat exchange element material Partition spacing plate-special treated paper
Cladding Galvanized steel sheet
Heat insulating material Self-extinguishing urethane foam
Motor DC brushless motor. Two units
Blower 220 mm diameter. Centrifugal fan
Filter material Non-woven fabrics fi lter (Gravitational method 82%, EU-G3)
Applicable air condition of setting envi-
ronment
The setting air condition shall be between -10°C to 40°C, 80%RH or less.
Applicable air condition range of outdoor
and indoor
OA temperature shall be -15°C to 40°C, 80%RH or less, with general air
conditioning room environment.
Functions
Lossnay ventilation fi ve speeds / Bypass ventilation (fi ve speeds + power)
Weight 48 kg
Frequency / Power source 50 Hz / Single phase 220 to 240 V
Ventilation mode
Lossnay (Energy recovery) ventilation Bypass ventilation
Fan speed (230 V) 1 2 3 4 5
Power 12345
Current [A] 1.17 0.67 0.35 0.20 0.13 1.80 1.20 0.70 0.35 0.20 0.13
Power Consumption [W] 165 90 41 22 14 265 164 90 40 21 14
Air volume [m3/h] 395 305 215 144 90 468 395 305 215 144 90
[l/s] 110 85 60 40 25 130 110 85 60 40 25
External static pressure [mmH2O] 10.2 6.1 3.1 1.5 0.7 13.8 10.2 6.1 3.1 1.5 0.7
[Pa] 100 60 30 15 7 135 100 60 30 15 7
Temperature exchange effi ciency [%] 77.5 81.5 85.5 88 90 ------
Enthalpy exchange
effi ciency [%]
Heating 71 75 79 82 84 ------
Cooling 68 72.5 77 80.5 83 ------
Noise [dB]
Measured at 1.5 m under the center
of panel in an anechoic chamber
31 26.5 21 18 18 35 31 26.5 21 18 18
Starting current 2.5 A or less
Insulation resistance 10 M
Ω or more (500 V megger)
Dielectric strength AC 1500 V 1 minute

─6 ─
4. Outside dimensions
Unit (mm)

─7 ─
5. Electrical wiring diagram
Thisproductmustbeconnectedtoallpolemainswitchwithatleast3mmdisconnection.

─8 ─
300 to 340 V DC
(D1)
Fan drive power supply
Reactor
(CN4, CN5)
GND
(C14)
LED 3 (green)
䍃During EA fan operation: lit
䍃During an error: blinking
Fuse
(6.3 A / 250 V)
Motor for
Bypass damper
220 to 240 V AC
(CN3)
Power supply
220 to 240 V 50 Hz
(CN1)
LED 2 (red)
䍃During SA fan operation: lit
䍃During an error: blinking
Transformer
input
(CN2)
Communication
signal between
the circuit boards.
(CN10)
SA fan drive
output
(CN6)
EA fan motor
sensor signal
(CN9)
5 V
0 V
Current waveform of the fan drive output
(Current of each line)
Although the current cycle and value varies
with the operational status, each current waveform
is a sine wave with a phase difference by 120 degrees.
Note) Noise is included in the actual waveform.
Voltage waveform of the fan motor sensor signal
(Voltage between the lead wires of the
connectors 2, 3, 4 and GND)
U Line current V Line current W Line current
U
V
W
The voltage cycle varies with the operational
status (rotational frequency).
Each signal has 50 % duty cycle of H (5 V) and L (0 V),
and there is a phase difference by 120 degrees.
Note) Noise is included in the actual waveform.
●CAUTION
Live parts of the large PCB is not insulated from the power supply.
Even after turning off the power, the capacitors on the circuit boards are still charged.
Wait more than 5 minutes before servicing.
EA fan drive
output
(CN7)
5 V DC
(C14)
SA fan motor
sensor signal
(CN8)
15 V DC
(IC5)
6. Basic circuit diagrams
Circuit board diagrams and check points
(1) Large printed circuit board (PCB) (Left)

─9 ─
(2) Small PCB (right)
Communication
signal between
the circuit boards.
(CN15)
Transformer output
11 V to 20 V AC
(CN14)
5 V DC
(C20)
SW1
12 V DC
(IC6)
GND
(C20)
Thermistor
(return air, outside air)
(CN16)
Damper position detector
(CN17)
䍃during energy recovery ventilation: 12 V DC
䍃during bypass ventilation: 0 V
Fan speed selection
(TM2 1 to 4, TM3 5)
Power bypass
condition selection
(TM3 PB)
During an error: 0 Ω
Normal: Open
(TM4 10, 11)
During operation: 0 Ω
When stopped: Open
(TM4 8, 9)
Ventilation priority
mode selection
(TM3 V)
LED 1 (red)
䍃Normal: lit
䍃During an error: blinking
LED 11 (green)
䍃During trial operation: lit
䍃During an error: blinking
SW2

─10 ─
7. Fundamentals of operation
Description of the PCB
(1) Air volume control
Fan speed selection
(TM2, TM3) Operation
Air volume
(Reference value under rated static pressure)
(m3/h) (l/s)
All contacts : OFF Stop 0 0
Speed 1 (Contact between 1 and COM) : ON
Running
395 110
Speed 2 (Contact between 2 and COM) : ON 305 85
Speed 3 (Contact between 3 and COM) : ON 215 60
Speed 4 (Contact between 4 and COM) : ON 144 40
Speed 5 (Contact between 5 and COM) : ON 90 25
Power bypass (Contact between PB and COM) : ON 468 130
1 Power bypass will be enabled when any of fan speed contacts (1 to 5) are ON. (The fan will not operate
when only the power bypass contact is turned ON.)
2 It needs 5 seconds to change air volume (including OFF) after the fan speed is selected.
3 When multiple fan speeds are selected simultaneously, the higher fan speed will be performed.
Fan speed fine-tuning
Fan speed can be fine-tuned by the dip switch SW 2 on the circuit board.
SW 2
ON OFF Operation
2
1
or
2
1
All supply air fan speeds are default settings.
2
1
Each of the supply air fan speed settings except
power bypass mode is increased.
2
1
Each of the supply air fan speed settings is
decreased.
4
3
or
4
3
All exhaust fan speeds are default settings.
4
3
Each of the exhaust fan speed settings except
power bypass mode is increased.
4
3
Each of the exhaust fan speed settings is
decreased.
Automatic air volume increasing during bypass setting
Fan speed will automatically increase 1 step higher than its present speed if both conditions are met:
• The dip switch SW 1-7 on the circuit board is ON.
• Operation mode is switched to bypass ventilation from energy recovery ventilation (with a summer criteria)
in automatic ventilation mode.
Example 1 : Speed 3 operation Speed 2 operation
Example 2 : Speed 1 operation Power bypass operation
(If the operation mode is switched to energy recovery ventilation from bypass ventilation, fan speed will
return to its original speed.)

─11 ─
Operation mode OA temperature SA fan EA fan
Normal -10°C <OA temperature Continuous running
1 2
Continuous running
SA intermittent
-15°C <OA temperature -10°C
Repeat 10 min. stop / 60 min. running
1 2
Continuous running
SA stopped OA temperature -15°C Repeat 55 min. stop / 5 min. running
1 2
Continuous running
3
1 The operation mode will be decided 5 minutes after the normal operation during startup.
2 The running condition does not change while the SA fan stops or 1 minute after startup. (OA temperature
is voided.)
3 When the switch SW 1-3 is on, the EA fan operates at fan speed 5 during 55-minute stop of the SA fan.
Cold region operation mode
When using the unit in cold region, set the air supply (SA)fan in the SA intermittent operation mode to pre-
vent the Lossnay core from freezing. The fan operation is based on the measured outside air (OA) tempera-
ture as below.
(2) Damper motor control
Automatic ventilation mode
Automatic ventilation algorithm patterns are switched by the OA • RA (return air) thermistor and function set-
ting switch SW 1-6.
Function setting switch SW1-6 OA temperature criteria
in the summer season Automatic ventilation algorithm
OFF (factory setting) 17°C or higher Automatic ventilation pattern 1 (chart 1)
ON 28°C or higher Automatic ventilation pattern 2 (chart 2)
Power bypass mode
When the TM3 PB contact is turned on with any fan speed contacts (1 to 5) on, operation mode will be
switched to bypass ventilation. Then, fan speed will be also increased to Power bypass speed.
Ventilation priority mode
When the TM3 V contact is turned on with any fan speed contacts (1 to 5) on, operation mode (energy re-
covery or bypass) can be fixed by the function setting switch SW 1-4. (Fan speed will not be changed in the
bypass ventilation mode.)
Function setting switch SW1-4 Ventilation priority mode
OFF (factory setting) Bypass ventilation fixed
ON Energy recovery ventilation fixed
Prohibition of the bypass ventilation
In the case of the situations below, bypass ventilation will be disabled, and energy recovery ventilation set-
ting will be activated.
a. OA temperature 8°C (for dew condensation prevention)
b. OA • RA thermistor failure.

─12 ─
Automatic ventilation algorithm temperature chart
<Pattern 1>
Chart 1. Automatic ventilation algorithm temperature chart during the switch SW 1-6 OFF setting.
6
8
10
12
14
16
18
20
22
24
26
28
30
6 8 10 12 14 16 18 20 22 24 26 28 30
Indoor temperature °C
Outdoor temperature °C
Bypass
ventilation
Energy recovery
ventilation
Undetermined area
6
8
10
12
14
16
18
20
22
24
26
28
30
6 8 10 12 14 16 18 20 22 24 26 28 30
Indoor temperature °C
Outdoor temperature °C
Bypass
ventilation
Energy recovery
ventilation
Undetermined area
When an outdoor temperature has not reached 17ºC
within 24 hours
When an outdoor temperature has reached 17ºC or higher
within 24 hours
Chart 2. Automatic ventilation algorithm temperature chart during the switch SW 1-6 ON setting.
6
8
10
12
14
16
18
20
22
24
26
28
30
6 8 10 12 14 16 18 20 22 24 26 28 30
Indoor temperature °C
Outdoor temperature °C
Bypass
ventilation
Energy recovery
ventilation
Undetermined area
6
8
10
12
14
16
18
20
22
24
26
28
30
6 8 10 12 14 16 18 20 22 24 26 28 30
Indoor temperature °C
Outdoor temperature °C
Bypass
ventilation
Energy recovery
ventilation
Undetermined area
When an outdoor temperature has not reached 28ºC
within 24 hours
When an outdoor temperature has reached 28ºC or higher
within 24 hours
<Pattern 2>
Undetermined area
When operation starts under this condition, energy recovery ventilation will be activated.
When this condition is reached after operation starts, the current ventilation mode is maintained.

─13 ─
(3) Operation monitor output
When the function setting switch SW 1-2 (for operation monitor output with delay function) is set to OFF, and
the switch SW 1-5 (for operation monitor output) is set to ON, the operation monitor signal can be output from
the monitor terminal block and (TM4) on the circuit board.
SW 1-2 OFF
SW 1-5 ON
Signal type Uncharged a-contact
Contact specifications Maximum load 220 to 240 V AC 2 A
24 V DC 2 A
Minimum load 5 V DC 100 mA
Operation Stopping Monitor output : Off (contact : open)
Running Monitor output : On (contact : close)
(4) Operation monitor output with delay function
When the function setting switch SW 1-2 (for operation monitor output with delay function) is set to ON, the op-
eration monitor signal from the monitor terminal block and (TM4) on the circuit board is shown as below.
SW 1-2 ON
Signal type Uncharged a-contact
Contact specifications Maximum load 220 to 240 V AC 2 A
24 V DC 2 A
Minimum load 5 V DC 100 mA
Operation
OA temperature -5°C Monitor output : On (contact : close) 10 seconds after air
supply fan operates
OA temperature 15°C Monitor output : Off (contact : open)
The fan continues to operate for 3 minutes, after operation monitor output has been
OFF by the Lossnay stopping control.
(5) Malfunction monitor output
The malfunction monitor signal can be output from the monitor terminal block and (TM4) on the circuit
board.
Signal type Uncharged a-contact
Contact specifications Maximum load 220 to 240 V AC 2 A
24 V DC 2 A
Minimum load 5 V DC 100 mA
Operation Normal Monitor output : Off (contact : open)
During an error Monitor output : On (contact : close)

─14 ─
(6) Trial operation function
This is a function for operating the Lossnay without external signals (contact signals). With this function, con-
necting condition of the AC power supply line and the wirings can be confirmed. Also, the Lossnay can be
forced to operate in case of system down.
How to set Turn on the trial operation switch SW 1-1.
SA fan operation Speed 1
EA fan operation Speed 1
Operation mode Energy recovery ventilation, after 1 minute bypass ventilation
LED 11 Lit
Operation monitor output
(TM4 and )
When SW 1-2 (Operation monitor output with delay function) is ON, or
SW 1-5 (Operation monitor output) is ON,
Monitor output : On (contact : close)
(7) LED display
Small PCB (right) Large PCB (left)
LED Display Condition LED Display Condition
LED 1 (red)
Unlit 1No power supplied
LED 2 (red)
Unlit SA fan stopping
Lit Power supplied Lit SA fan running
Blinking Error Blinking Error
LED 11 (green)
Unlit 1Normal
LED 3 (green)
Unlit EA fan stopping
Lit In trial operation Lit EA fan running
Blinking Error Blinking Error
1 When one of LED 1 and LED 11 is blinking, the other one will be unlit.
2 In case multiple errors have occurred at the same time, each LED will blink simultaneously.

─15 ─
(8) Function setting switches
1 Trial operation (Refer to (6) (page 14).)
SW1
OFF ON Operation
1 Normal operation
1 Trial operation
SW1
Trial operation
Operation monitor output with delay function
Setting for exhaust fan in cold region operation mode
Ventilation priority mode during ventilation setting input on
Operation monitor output
Bypass auto ventilation priority setting
Automatic air volume increasing during bypass setting
Not to used
Decreasing exhaust fan power
Increasing exhaust fan power
Decreasing supply fan power
Increasing supply fan power
2 Operation monitor output with delay function (TM4 )
SW1
OFF ON Operation
2 Not available
2 Available (Refer to (4) (page 13).)
3 Exhaust fan speed setting in cold region operation mode
(Refer to (1) (page 11).)
SW1
OFF ON Operation
3 Not fixed
3 Exhaust fan : speed 5 fixed
4 Ventilation priority mode during ventilation setting input on
(Refer to (2) (page 11).)
SW1
OFF ON Operation
4 Bypass ventilation mode fixed
4 Lossnay (Energy recovery) ventilation mode fixed
* Below 8 °C , even SW1-4 is fixed any setting, ventilation mode should be Lossnay
(Energy recovery) ventilation.
5 Operation monitor output (TM4 )
SW1
OFF ON Operation
5 Not available
5 Available (Refer to (3) (page 13).)
* During SW1-2 on, operation monitor output is prior to “ 2 operation monitor output
with delay function”.
6 Bypass automatic ventilation priority setting (Refer to (2)
(page 12).)
SW1
OFF ON Operation
6
When outdoor temperature is 17°C or higher
within 24 hours, then bypass ventilation starts by
comparison OA and RA.
6
When outdoor temperature is 28°C or higher
within 24 hours, then bypass ventilation starts by
comparison OA and RA.
7 Automatic air volume increasing during bypass setting
SW1
OFF ON Operation
7 Not increasing.
7
When unit is in bypass operation except power
bypass mode, the unit fan speed is automatically
increased 1 step.
8 Fan speed fine-tuning
SW2
ON OFF Operation
2
1
or
2
1
All supply air fan speeds are default settings.
2
1
Each of the supply air fan speed settings except
power bypass mode is increased.
2
1
Each of the supply air fan speed settings is
decreased.
4
3
or
4
3
All exhaust fan speeds are default settings.
4
3
Each of the exhaust fan speed settings except
power bypass mode is increased.
4
3
Each of the exhaust fan speed settings is
decreased.
SW2
All switches are OFF at factory setting.

─16 ─
8. Troubleshooting
Work precautions
• When removing or touching a transformer, printed circuit board or other parts, make sure to turn off the
power supply isolator. Even after disconnecting the power supply isolator, the voltage is still high in the ca-
pacitors on the printed circuit boards. Wait more than 5 minutes, and make sure the voltage is low by using
a tester, before servicing.
• When removing the circuit board, always hold it at both ends and remove carefully so as not to apply force
to the surface mounted parts.
• When removing the circuit board, be careful of the metal edges on the board.
• When removing or inserting the connectors for the circuit board, hold the entire housing section. Never pull
on the lead wires.
• When servicing, be sure the failure can be repeated twice or three times before starting repairs.
• When reconnecting the power supply, wait more than 5 minutes after power-off, and then turn it on again.
• If there is a suspected printed circuit board malfunction, check for disconnected wires in the print pattern,
burnt parts or discoloration.
• If the printed circuit board has been replaced, make sure that the switch settings on the new board are the
same as the old board.
No. Checkpoints
1 Do the wiring diameters and capacity of the motor breaker and the earth leakage breaker meet specifi-
cations?
2 Is the specified power (220 to 240 V AC 50 Hz) supplied to the power terminal (TM1)?
3 Do the wirings for the fan speed and bypass condition selections meet specifications?
• Contact: 12 V DC 10 mA
• Diameter of cables : 0.5 mm2to 1.0 mm2
• Maximum length : 20 m from the terminal block
• Wire peeling length : 9-10 mm
4 Are the wirings for fan speed and bypass condition selections correct?
5 Are the wires for fan speed and bypass condition selections more than 10 cm away from the power sup-
ply cable?
6 Are the connected terminal blocks of the wires for fan speed and bypass condition selections correct?
(TM2 1-4 and TM3 5 are for fan speed selection. TM3 PB and V are for bypass condition selection.)
7 Is each wire securely connected to the terminal blocks?
8 Are external signals correctly input to TM2 and TM3 on the circuit board?
9 Is the output capacity of the operation and malfunction monitors within rated range?
Operation monitor output : Maximum 220 to 240 V AC/ 24 V DC 2 A, minimum 5 V DC 100 mA
Malfunction monitor output : Maximum 220 to 240 V AC/ 24 V DC 2 A, minimum 5 V DC 100 mA
(1) Checkpoints for installation condition

─17 ─
(2) Troubleshooting and repair method
When any LEDs on the circuit boards are blinking
The type of failure is shown by the number of blinking times of LED 1 (red), LED 11 (green), LED 2 (red) and
LED 3 (green) on the circuit boards. The LED blink interval is 0.25 seconds for both lit and unlit. The display
duration is approximately 5 seconds.
5s
0.25s 0.25s0.25s
Lit
Unlit
Failure display example (2 blinks)
Checklist of LED failure displays
LED 1
(red)
LED 11
(green)
LED 2
(red)
LED 3
(green)
Symptom Cause Corrective action
2
blinks
-1
blink -
SA fan over-
current failure
Overcurrent occurred
at the SA fan motor.
Turn off the power supply, wait more than 5
minutes, and then turn it on again.
SA fan motor mal-
function
Check the coil resistance of the fan motor.
If it has a defect, replace the fan motor.
Large circuit board
malfunction
Replace the circuit board if none of above
related actions works.
-2
blinks
-1
blink
EA fan over-
current failure
Overcurrent occurred
at the EA fan motor.
Turn off the power supply, wait more than 5
minutes, and then turn it on again.
EA fan motor mal-
function
Check the coil resistance of the fan motor.
If it has a defect, replace the fan motor.
Large circuit board
malfunction
Replace the circuit board if none of above
related actions works.
2
blinks
-3
blinks
-
Fan drive
voltage failure
(Undervoltage)
The power supply
voltage is low (150 V
AC or lower).
Check the power supply voltage.
(220 to 240 V AC 50 Hz)
Large circuit board
malfunction
Replace the circuit board if none of above
related actions works.
2
blinks
-4
blinks
-
Fan drive
voltage error
(Overvoltage)
The power supply
voltage is high (320 V
AC or higher).
Check the power supply voltage.
(220 to 240 V AC 50 Hz)
Large circuit board
malfunction
Replace the circuit board if none of above
related actions works.
2
blinks
-5
blinks
-
SA fan opera-
tion failure
The SA fan does not
rotate properly.
Check whether the fan turns by hand.
SA fan motor wire
connection error
Check the wiring of the connector (CN6) on
the circuit board and the fan motor.
SA fan motor mal-
function
Check the coil resistance of the fan motor.
If it has a defect, replace the fan motor.
SA fan motor sensor
malfunction
Check the signal voltage of the fan motor sen-
sor. If it has a defect, replace the fan motor.
Large circuit board
malfunction
Replace the circuit board if none of above
related actions works.
In case multiple errors have occurred at the same time, each LED will blink simultaneously.
When reconnecting the power supply, wait more than 5 minutes after power-off, and then turn it on again.

─18 ─
LED 1
(red)
LED 11
(green)
LED 2
(red)
LED 3
(green)
Symptom Cause Corrective action
-2
blinks
-5
blinks
EA fan opera-
tion failure
The EA fan does not
rotate properly.
Check whether the fan turns by hand.
EA fan motor wire
connection error
Check the wiring of the connector (CN7) on
the circuit board and the fan motor.
EA fan motor mal-
function
Check the coil resistance of the fan motor.
If it has a defect, replace the fan motor.
EA fan motor sensor
malfunction
Check the signal voltage of the fan motor sen-
sor. If it has a defect, replace the fan motor.
Large circuit board
malfunction
Replace the circuit board if none of above
related actions works.
2
blinks
-
6 or
7
blinks
-
SA fan motor
sensor failure
Wire connection error
of SA fan motor sensor
Check the wiring of the connector (CN8) on
the circuit board and the fan motor sensor.
SA fan motor sensor
malfunction
Check the signal voltage of the fan motor sen-
sor. If it has a defect, replace the fan motor.
Large circuit board
malfunction
Replace the circuit board if none of above
related actions works.
-2
blinks
-
6 or
7
blinks
EA fan motor
sensor failure
Wire connection error
of EA fan motor sensor
Check the wiring of the connector (CN9) on
the circuit board and the fan motor sensor.
EA fan motor sensor
malfunction
Check the signal voltage of the fan motor sen-
sor. If it has a defect, replace the fan motor.
Large circuit board
malfunction
Replace the circuit board if none of above
related actions works.
9
blinks
9
blinks
9
blinks
9
blinks
Communication
failure between
the circuit
boards 1
Connection error
between the circuit
boards
Check the connections of the connectors
(CN10, CN15) on the circuit boards.
The external signal
wires and power sup-
ply cable are too close.
Keep the wires for fan speed and bypass
condition selections more than 10 cm away
from the power supply cable.
Connection error of
transformer
Check the connection of the connectors
(CN2, CN14) on the circuit boards.
Transformer malfunc-
tion
Check the output of the transformer. If it has
a defect, replace the transformer.
Connection error of
reactor
Check the connection of the connectors
(CN4, CN5) on the circuit board.
Reactor malfunction Check the resistance of the reactor. If it is
open, replace the reactor.
Circuit boards mal-
function
Replace both circuit boards if none of above
related actions works.
3
blinks
---
Damper failure Damper operation
error
Remove the rod, and then check whether
the damper plate moves by hand.
For removing the rod, open the maintenance
cover and remove the guards from the unit.
Wire connection error
of the damper unit
Check the wiring of the connectors (CN3,
CN17) on the circuit boards and the damper
unit.
Connection error
between the circuit
boards
Check the connection of the connectors
(CN10, CN15) on the circuit boards.
1 Each LED does not blink simultaneously in some cases.
In case multiple errors have occurred at the same time, each LED will blink simultaneously.
When reconnecting the power supply, wait more than 5 minutes after power-off, and then turn it on again.

─19 ─
LED 1
(red)
LED 11
(green)
LED 2
(red)
LED 3
(green)
Symptom Cause Corrective action
4
blinks
---
OA thermistor
failure
Connector connection
error of thermistor
Check the wiring of the connector (CN16) on
the circuit board and the thermistor.
Thermistor malfunc-
tion
Check the resistance of the thermistor.
If it has a defect, replace the thermistor.
5
blinks
---
RA thermistor
failure
Connector connection
error of thermistor
Check the wiring of the connector (CN16) on
the circuit board and the thermistor.
Thermistor malfunc-
tion
Check the resistance of the thermistor.
If it has a defect, replace the thermistor.
8
blinks
---
External de-
vice error
(when the
switch SW 1-2
is ON)
The following condi-
tions developed.
•
OA temperature is
still -10°C or lower,
60 minutes after
the TM4 8,9 output
started.
• OA temperature is
15°C or higher within
15 minutes after
the TM4 8,9 output
started.
When external devices are connected,
check the external devices.
When external devices are not connected,
check the switch SW 1-2.
In case multiple errors have occurred at the same time, each LED will blink simultaneously.
When reconnecting the power supply, wait more than 5 minutes after power-off, and then turn it on again.
LED 1
(red)
LED 11
(green)
LED 2
(red)
LED 3
(green)
Contents Descriptions
Lit
2 ---
Power supplying to the circuit board Lit when the power is supplying to the circuit
board.
-Lit
2 --
Trial operation Lit during trial operation (SW 1-1 ON).
- - Lit - SA fan operation Lit during the SA fan operation.
- - - Lit EA fan operation Lit during the EA fan operation.
LED displays (Normal)
2 When one of LED 1 and LED 11 is blinking (during an error), the other one will be unlit.
All LEDs are temporarily lit just after power-on.

─20 ─
When the unit does not operate or operates irregularly
No. Symptom Cause Corrective action
1 The fans do not
operate.
Power is not supplied to the unit. Check the power supply.
(220 to 240 V AC 50 Hz)
Power supply voltage is out of rated
range.
Check the power supply.
(220 to 240 V AC 50 Hz)
• Improper connection or wiring of the
external signals.
• The type of external signals does not
match the connected terminal block.
Check the connections of the external
signal wires and the terminal blocks (TM2,
TM3).
TM2 1-4 and TM3 5 are for fan speed selection.
TM3 PB is for bypass condition selection.
TM3 V is for ventilation priority mode.
The type of external signals is incorrect.
(Uncharged a-contact)
Check the type of external signals.
The external device signals are not input. Check the external devices.
The signal cables from the external de-
vices are longer than specified.
Check the wiring length of the signal
cables. (Make sure the wiring length from
the external devices is within 20 m.)
The external signal wires and the power
supply cable are too close.
Keep the wires for fan speed and bypass
condition selections more than 10 cm
away from the power supply cable.
Malfunction of the circuit board, or the fan
motor
See the "Checklist of LED failure dis-
plays" (page 17).
2•The fans do not
stop.
• The fan speed
does not
change.
The trial operation switch SW 1-1 is ON. Check the trial operation switch SW 1-1.
The external device signals are input. Check the external devices.
The external signal wires and the power
supply cable are too close.
Keep the wires for fan speed and bypass
condition selections more than 10 cm
away from the power supply cable.
The signal cables from the external de-
vices are longer than specified.
Check the wiring length of the signal
cables. (Make sure the wiring length from
the external devices is within 20 m.)
3 Air volume chang-
es by itself.
The function setting switch SW 1-7
(Automatic air volume increasing during
bypass setting) is ON.
If energy recovery ventilation mode is au-
tomatically switched to bypass ventilation
with the switch SW 1-7 is ON, fan speed
will increase 1 step higher than its pres-
ent speed (with a summer criteria).
If the operation mode is switched to en-
ergy recovery ventilation, fan speed will
return to its original speed.
Refer to 7. (1) (page 10).
(This is not a failure.)
4 The SA fan pe-
riodically stops
operating.
•
When -15°C < OA temperature -10°C,
the SA fan regularly stops for 10 minutes
to prevent the Lossnay core from freez-
ing.
• When OA temperature is -15°C or lower,
The SA fan stops to prevent the Lossnay
core from freezing.
Refer to 7. (1) (page 11).
(This is not a failure.)
5 The SA fan pe-
riodically stops
operating, and the
EA fan air volume
decreases.
When OA temperature is -15°C or lower,
the SA fan stops operating to prevent the
Lossnay core from freezing.
Then, the EA fan runs at speed 5 if the
switch SW 1-3 is ON.
Refer to 7. (1) (page 11).
(This is not a failure.)