Toshiba MMU-P0121H Service Manual page 87

Check code
[bb]
Discharge temperature TD2 alarm
In cooling
*
only model
In there blockage in
the check valve to interrupt
the liquid line?
NO
Replace the check valve
Check code
[bd]
Mg-SW protective operation
Is contact of Mg-SW defunct?
NO
Is resistance value characteristics
of TD sensor normal?
YES
Are output voltage characteristics
of Pd sensor/Ps sensor normal?
YES
Insufficient refrigerant, blockage
1. Outdoor unit service valve closed
2. Blockage of check valve to interrupt the liquid line.
3. Outdoor PMV A error or cooling bypass PMV B error
4. TD sensor error
5. Insufficient refrigerant, blockage in pipe
Are gas pipe,liquid pipe,
YES
and service valve of the
outdoor unit fully open?
YES
Is outdoor PMV A normal?
1. Connector connection
2. Wiring
3. Coil
4. Valve unit
5. Outdoor P.C. board
YES
YES
Is cooling bypass PMV B normal?
YES
Are resistance characteristics
of TD2 sensor normal?
YES
Is wiring correct?
YES
Insufficient refrigerant,
blockage, pipe breakage
1. Mg-SW contact deposit protective operation
2. TD sensor error
3. Pd sensor/Ps sensor error
4. Insufficient refrigerant, blockage in pipe
YES
NO
NO
3-84
Operation cause
NO
Open service valve fully.
NO
Repair outdoor PMV A.
NO
Cooling bypass PMV B error
NO
Replace TD2 sensor.
NO
Set normal wiring.
Check miswiring of the outdoor unit
(
according to miswiring check function.
Check there is no blockage or pipe
(
breakage, and then addrefrigerant according
to judgment of refrigerant amount.
Operation cause
Turn off power supply,
and replace Mg-SW.
Sensor error
Sensor error
)
)