Mitsubishi Electric PU(H)Y-P250YGM-A Service Handbook page 159

[ IX Troubleshooting ]
(4) In case of SV1 (Bypass valve)
This solenoid valve opens when powered (Relay ON).
1) At compressor start-up, the SV1 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 SV1 downstream piping temperature while
the valve is being powered.Even when the valve is closed, 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.)
(5) In case of SV3 (Bypass valve) (Only P500 model)
This solenoid valve opens when powered (Relay ON).
The valve is normally powered while No.2 Comp is being stopped. (When the discharge temperature of No.1 Comp ex-
ceeds 110°C, the valve may be turned off.)
To check whether the valve is open or closed, check the change of the SV3 downstream piping temperature while the
valve is being powered. When the valve is open, high-temperature gas will run. Do not touch the pipe when checking the
temperature.
(6) In case of SV5b (2-way switching valve)
This 2-way valve is closed when powered. Check the LED display and the switching sound to check whether the valve
has no faults.When cooling, the switching coincides with 21S4b. When it is difficult to check by the sound, check the tem-
perature at the front and the back of the pipe to check whether the refrigerant is flowing.
∗Do not give an impact from the outside, as the outer hull will be deformed, leading to the malfunction of the inner valve.
(7) In case of SV5c (2-way switching valve) (Only P500 model)
This 2-way valve is closed when powered. Check the LED display and the switching sound to check whether the valve
has no faults.When cooling, the switching coincides with 21S4b. When it is difficult to check by the sound, check the tem-
perature at the front and the back of the pipe to check whether the refrigerant is flowing.
∗Do not give an impact from the outside, as the outer hull will be deformed, leading to the malfunction of the inner valve.
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