Mitsubishi Electric CITY MULTI P500YMF-C Service Handbook page 44

2) Bypass solenoid valves (SV1, SV4) [Both SV1 and SV4 are on (open)]
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
* Example of operation of SV1
Compressor
Bypass
solenoid
Start
valve (SV1)
(4-minute)
3) Capacity control solenoid valve (SV22, SV32). :P500 only
• Operation of solenoid valve
Solenoid valve
Status
Full-load
(Operating at 100 %
capacity)
Un-load
(Capacity control
operation)
ON
ON for 4 minutes
ON for 3 minutes
ON during oil recovery operation af-
ter continuous low-frequency com-
pressor operation.
2
Pd 27.5 kg/cm
(2.70 MPa)
Thermo. Thermo.
OFF ON
(2-minute)
SV22 SV32
Coil Valve Coil Valve
OFF Open OFF Closed
ON Closed ON Open
SV1
OFF
ON
ON
Ps < 1.0 kg/cm
—
2
Pd 24 kg/cm G
G
Pd
(2.35 MPa) and
after 30 seconds.
• Td >
—
and
• Pd > 20 kg/cm
or
Ps < 3.5 kg/cm
Defrost
(4-minute)
–42–
SV4a
ON
—
—
—
Normally ON
—
2
G Ps 2.0 kg/cm
(0.098 MPa)
(0.196 MPa)
2
27 kg/cm G Pd 24 kg/cm
(2.65 MPa)
(2.35 MPa) and after
30 seconds
130 C
(No. 1 compressor)
Td
115 C
(No. 2 compressor)
2 G
(1.96 MPa)
2 G
(0.34 MPa)
Stop
(3-minute)
SV22
SV32
COMP
OFF
2 G
2 G
115 C
(No. 1 compressor)
100 C
(No. 2 compressor)