Troubleshooting Solenoid Valve Problems - Mitsubishi Electric PURY-M200YNW-A1 Service Handbook

[8-6 Troubleshooting Solenoid Valve Problems ]

8-6

Troubleshooting Solenoid Valve Problems

Check whether the output signal from the control board and the operation of the solenoid valve match.
Setting the self-diagnosis switch (SW4) as shown in the figure below causes the ON signal of each relay to be output to the LED's.
Each LED shows whether the relays for the following parts are ON or OFF. LEDs light up when relays are on.
The circuits on some parts are closed when the relays are ON. Refer to the following instructions.
SW4 (SW6-10:OFF)
SW4
ON
2 3 4 5 6 7 8 9 10
1
SW4
ON
1 2 3 4 5 6 7 8 9 10
ON
1 2 3 4 5 6 7 8 9 10
When a valve malfunctions, check if the wrong solenoid valve coil is not attached the lead wire of the coil is not disconnected,
the connector on the board is not inserted wrongly, or the wire for the connector is not disconnected.
(1) In case of 21S4a, 21S4b, 21S4c (4-way switching valve)
About this 4-way valve
When not powered:
Conducts electricity between the oil separator outlet and heat exchanger AND the gas ball valve (BV1) and the accumulator to com-
plete the circuit for the cooling cycle.
When powered:
The electricity runs between the oil separator and the gas ball valve, and between the heat exchanger and the accumulator. This
circulation is for heating.
Check the LED display and the intake and the discharge temperature for the 4-way valve to check whether the valve has no faults
and the electricity runs between where and where.Do not touch the pipe when checking the temperature, as the pipe on the oil sep-
arator side will be hot. (Before checking the inlet and outlet temperatures, check that LEV2a, LEV2b and LEV2c are open. Refer to
[8-8 Troubleshooting LEV, FCV Problems].)
Do not give an impact from outside, as the outer hull will be deformed leading to the malfunction of the inner valve.
(2) In case of 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 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.)
(3) In the case of SV2 (Bypass valve)
This solenoid valve opens when powered (Relay ON).
The relay turns on in the following cases:
63HS1 is above 3.43 MPa (497 psi) even when the compressor operates at the minimum frequency in the heating-only or
heating-main mode.
63LS is below 0.25 MPa (36 psi) and 63HS is below 1.47 MPa (213 psi) within 8 minutes after the recovery from defrosting
in the heating-only or heating-main mode, or 3 minutes after and within 12 minutes after the start of the compressor. To see
whether the valve is open or closed, check the change in the SV2 downstream piping temperature while the valve is being
powered. Do not touch the pipe to check the valve status because hot gas flows while the valve is open.
22
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LD1 LD2
Upper 21S4a
Lower
Upper
Lower
The figure at left shows that the switches 1 through 5 are set to ON and 6 through 10 are set to OFF.
Display
LD3 LD4 LD5
SV1a
21S4b
21S4c
LD6 LD7 LD8
SV2
BS_08_L