Mitsubishi Electric City Multi CMB-P1016NU-G, Руководство по обслуживанию

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[
IX
Troubleshooting ]
-3- Solenoid Valve
Check whether the output signal from the control board and the operation of the solenoid valve match.
Setting the self-diagnosis switch (SW1) 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.
∗
The circuits on some parts are closed when the relays are ON. Refer to the following instructions.
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 (4-way switching valve)
About this 4-way valve
When not powered:
The electricity runs between the oil separator exit and the heat exchanger, and between the gas ball valve and the accu-
mulator. This circulation is for cooling.
When powered:
The electricity runs between the oil separator and the gas ball valve, and between the heat exchanger and the accumu-
lator. This circulation is for heating.Refer to the refrigerant circuit diagram.
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 separator side will be hot.
∗
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 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.)
(3) SV4a -4d, SV7a-7c (Heat exchanger capacity control)
1) During Cooling-Only operation, at least one of the valves out of SV4a-4d, 7a, and 7b will come ON. Confirm the
operation of the solenoid valve by checking the LED and by listening for the operating sound.
2) During Heating-Only, Cooling-Main, or Heating-Main operation (PQRY only), at least one of the valves out of SV4a-
4d and 7a-7c will come ON. Operation of the solenoid valve can be checked on the LED display or by listening for
the operating sound.
3) Refrigerant flow is as shown in the figure below. The figure shows the flow of the high temperature (high-pressure)
gas/liquid refrigerant in the cooling or cooling only/cooling main mode, and the flow of the low temperature gas/
liquid refrigerant in the heating only/heating main mode. Refer to the refrigerant circuit diagram.Solenoid valves are
turned on and off depending on such factors as the capacity of the operating indoor units and outdoor temperature.
Check the LED monitor. Remove the SV coil, open the lid, and check the plunger. A pin face spanner wrench is
required.
ON
ON
ON
ON
SW1
1 2 3 4 5 6 7 8 9 1 0
Display
LD1 LD2 LD3 LD4 LD5 LD6 LD7 LD8
21S4a
CH11
52F
SV4a SV4b SV4c SV1
SV7a SV7b SV7c
SV4d
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10