Mitsubishi Electric CITY MULTI PUHY-400YMF-B, Service Handbook, Page: 64 / 204

–61–
Item
At compressor is started
Compressor stopped during cool-
ing or heating mode
After operation has been stopped
During defrosting ((*1) in Fig below)
During oil recovery operation
When low pressure (Ps) has
dropped during lower limit fre-
quency operation(15 minutes af-
ter start)
When the high pressure (Pd) is
risen up during lower limit fre-
quency operation (3 minutes after
starting)
When the discharge temperature
(Td) is risen up
Ps 2.0 kg/cm 2 G
(0.196 MPa)
Pd 24 kg/cm 2 G
(2.35 MPa) and after
30 seconds
Pd 20 kg/cm 2 G
(1.96 MPa)
* Example of operation of SV1
Compressor
Bypass
solenoid
valve (SV1)
(4-minute) (2-minute) (4-minute) (3-minute)
Start
Thermo.
OFF Thermo.
ON
Defrost
Stop
2) Bypass solenoid valves (SV1, SV4) [Both SV1 and SV4 are on (open)]
ON OFF
SV1
ON for 4 minutes
ON
ON for 3 minutes
ON
ON during oil recovery operation af-
ter continuous low-frequency com-
pressor operation.
—
—
—
ON
Ps < 1.0 kg/cm
2
G
(0.098 MPa)
Pd 27 kg/cm 2 G
(2.65 MPa)
ON when the high pres-
sure (Pd) exceeds the
control pressure limit.
OFF
SV4
—
—
—
Normally ON
—
3) Capacity control solenoid valve (SV22, SV32).
• Operation of solenoid valve
• SV22 and SV32 stand for SV2 and SV3 of the No. 2
compressor.
Solenoid valve
SV22
SV32
COMP
SV22 SV32
Coil Valve Coil Valve
OFF Open OFF Closed
ON Closed ON Open
Status
Full-load
(Operating at 100 %
capacity)
Un-load
(Capacity control
operation)
Pd 27.5 kg/cm 2 G
(2.70 MPa)
Pd 24 kg/cm
2
G
(2.35 MPa) and
after 30 seconds.
130
°
C
(No. 1 compressor)
115
°
C
(No. 2 compressor)
• Td >
and
• Pd > 20 kg/cm 2 G
(1.96 MPa)
or
Ps < 3.5 kg/cm
2
G
(0.34 MPa)
115
°
C
(No. 1 compressor)
100
°
C
(No. 2 compressor)
Td