[A7] Suction Temperature (Ts) Alarm; [Aa] High Pressure Sensor (Pd) Short Circuit - Toshiba HFCR407C Service Manual

Check code
[A7]
Suction temperature (TS) alarm
Are the gas pipe and liquid pipe
service valves of the outdoor unit
fully open ?
Yes
Is there a blockage in the PMV
assembly on the liquid line ?
No
Are the resistance
characteristics of TS sensor
normal ?
Yes
Insufficient refrigerant, blockage,
pipe breakage.
Check code
[AA]
High pressure sensor (Pd) short circuit
If there is an abnormal output voltage of Pd sensor: Check connector circuit (Pd sensor: CN501) and output
voltage of the sensor.
If the sensor is normal, replace the outdoor interface PC board.
Troubleshooting
Diagnostic procedure for check code
No
Yes
No
Operation cause
1. Outdoor unit service valve closed
2. Blockage PMV assembly on the liquid line
3. TS sensor error
4. Insufficient refrigerant, blockage in pipe
Operation cause
Pd sensor output voltage alarm
99
Open valves fully.
Replace both the PMVs.
Replace TS sensor.
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