Toshiba MMU-P0121H Service Manual page 88

Check code
[bE]
Low-pressure protective operation
Does cooling indoor
fan normally operate?
YES
Is there blockage of indoor
filter or heat exchanger?
NO
Does heating outdoor
fan operate normally?
YES
Is there blockage on
outdoor heat exchanger?
NO
Are gas pipe,liquid pipe,
and service valve of the
outdoor unit fully open?
YES
Is characteristics of
low-pressure sensor normal?
YES
Is SV2 bypass circuit normal?
YES
Is wiring correct?
YES
Insufficient refrigerant,
blockage, pipe breakage
1. Ps sensor error
2. Service valve closed
3. Indoor fan capacitor error
4. Indoor/outdoor PMV blockage
5. Indoor heat exchanger blockage
6. SV2 circuit
7. Incorrect wiring of communication cable between indoor
and outdoor units
Are the following items related
to indoor fan motor normal?
NO
1. Connection
2. Capacitor
3. Motor
YES
YES
Is outdoor fan motor normal?
NO
1. Connector connection
2. Heat exchanger
3. Motor
YES
YES
NO
NO
NO
NO
(Check miswiring of the outdoor unit according to miswiring check function.)
( Check there is no blockage or pipe breakage, and then add
refrigerant according to judgment of refrigerant amount.
3-85
Operation cause
NO
Repair defective position.
Check indoor P.C. board.
Defective
Cleaning
NO
Repair defective position.
Check outdoor P.C. board.
Defective
Cleaning
Open service valve fully.
Replace low-pressure sensor.
Modify SV2 bypass circuit.
Set normal wiring.
)
Replacement
Replacement