Mitsubishi Electric PUHY-HP72 Service Handbook page 220

[8-6 Troubleshooting Solenoid Valve Problems ]
(3) SV1a (Bypass valve)
This solenoid valve opens when powered (Relay ON).
1) At compressor start-up, the SV1a turns on for 4 minutes, and the operation can be checked by the self-diagnosis LED display
and the closing sound.
2) To check whether the valve is open or closed, check the change of the SV1a downstream piping temperature while the valve
is being powered. Even when the valve is open, high-temperature refrigerant flows inside the capillary next to the valve.
(Therefore, temperature of the downstream piping will not be low with the valve closed.)
(4) SV2 (solenoid valve)
This solenoid valve is a switching valve that opens when energized. Proper operation of this valve can be checked on the LED
and by the switching sound.
(5) SV9 (Solenoid valve)
This solenoid valve is a switching valve that opens when energized. Proper operation of this valve can be checked on the LED
display and by the switching sound.
(6) SV10 (Solenoid valve)
This solenoid valve is a switching valve that opens when energized. Proper operation of this valve can be checked on the LED
display and by the switching sound.
Do not give an impact from outside, as the outer hull will be deformed leading to the malfunction of the inner valve.
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chapter 8 -