Toshiba MMU-P0121H Service Manual page 60

Check code
[08]
4-way valve reversal alarm
Is 4-way valve coil
connector connected?
YES
Is 4-way valve cool normal?
YES
Are connectors of TS1, TE1, Pd,
and Ps sensors connected?
YES
Are resistance value
characteristics of TS1 and
TE1 sensors normal?
YES
Are output voltage
characteristics of Pd and
Ps sensors normal?
YES
Is there no problem on wiring
of fixed-speed compressor?
YES
Reset power supply and
perform trial heating operation.
Does 4-way valve operate?
NO
Is fixed-speed
compressor activated?
YES
4-way valve error
1. 4-way valve operation error
2. TS1sensor/TE1 sensor error
3. Pd sensor/Ps sensor error
4. Fixed-speed compressor Mg-SW operation error
NO
NO
NO
NO
NO
NO
Does refrigerant bypass
YES
from discharge to suction
on 4-way valve?
NO
Does OL of Mg-SW operate?
Does IOL of fixed-speed
compressor operate?
3-57
Operation cause
Modify connector connection.
(4-way valve coil : CN317)
Modify connection of connectors.
TS1 sensor : CN504
TE1 sensor : CN505
Pd sensor : CN501
Ps sensor : CN500
NO
YES
YES
NO
YES
NO
4-way valve cool error
Sensor error
Sensor error
Correct wiring.
Restart the operation if a
trouble has not occurred
in trial operation.
Check 4-way valve.
Restart the operation
after manual reset.
Restart the operation after
compressor IOL reset
(automatic reset).
Mg-SW error