Super Multi System - Toshiba

56
Troubleshooting
Diagnostic procedure for check code
Check code Operation cause
[A7] 1. Outdoor unit service valve closed.
Suction temperature (TS) alarm (>40°C) 2. Blockage PMV assembly on the liquid line.
3. TS pressure switch error.
4. Insufficient refrigerant, blockage in pipe.
Are the gas pipe and liquid pipe
service valves of the outdoor unit
fully open ?
�
Is there a blockage in the
expansion valve on the liquid line?
�
Yes
No
Are the characteristics of TS
pressure switch normal?
(N/C type)
Yes
�
Insufficient refrigerant, blockage,
pipe breakage.
No
Yes
No
Check code
[AA]
Operation cause
High pressure sensor (Pd) short circuit Pd sensor output voltage alarm
�
�
�
Open valves fully.
Replace expansion valve.
Replace TS pressure switch.
If there is an abnormal output voltage of Pd sensor: Check connector circuit (Pd sensor: PJ7) and output
voltage of the sensor.
If the sensor is normal, replace the outdoor interface PC board.
Sensor characteristics:
Input 12 V DC (± 10%) across red and black leads of the pressure sensor.
Output 0.5 to 4.5 V at 0 to 2.45 MPa across white and black leads of the pressure sensor.