(1) In the case of SV1 (Bypass valve)
This solenoid valve opens when powered (Relay ON).
(a) When the compressor starts, SV1 is ON for 4 minutes, check operation by whether the solenoid valve is emit
ting an operating noise.
(b) Changes in the operating condition by solenoid valve operation can be confirmed by the temperature of the
bypass circuit and the sound of the refrigerant.
(c) SV1 goes on in accordance with the rise in high pressure in the cooling and heating mode, check operation
by LED display and the operating noise emitted by the solenoid valve.
(2) In the case of SV2 (Bypass valve)
This solenoid valve opens when powered (Relay ON).
In the case of heating-only or heating-main, the valve turns on when the low pressure(LPS) becomes 0.25MPa or
less in 5 minutes after the compressor starts.
To check whether the valve is open or closed, check the change of the SV2 downstream 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.
(3) In the case of SV3 (Bypass valve) (Only P450-P650 types)
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 exceeds 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.
SW1
LED
1
2
3
4
5
6
7
8
SV1
SV2
SV4a
SV4b
SV4d
SV4c
SV3
SV5b
SV5a
52F
21S4a
21S4b
CH11
CH12
1 2 3 4 5 6 7 8 9 10
ON
1 2 3 4 5 6 7 8 9 10
ON
1 2 3 4 5 6 7 8 9 10
ON
Check if the control board’s output signals and the operation of the solenoid valves 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. When a LED lights up, it indicates that
the relay is ON.
✻
The circuit is closed when the relay is ON depending on parts. Refer to the following instructions.
When whatever valves malfunction, check whether the solenoid valve coil is not attached wrongly, 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.
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3. Solenoid valve