Mitsubishi Electric CITY MULTI PUHY-400YMF-B Service Handbook page 99

2) Bypass solenoid valves (SV1, SV4) [Both SV1 and SV4 are on (open)]
<Variable capacity unit>
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 saturation
temperature (TH2) has dropped
during lower limit frequency opera-
tion(15 minutes after 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)
ON
ON for 4 minutes
ON for 3 minutes
ON during oil recovery operation after con-
tinuous low-frequency compressor opera-
tion.
Pd 27.5 kg/cm 2 G
(2.70 MPa)
Thermo. Thermo.
OFF ON
(2-minute)
SV1
OFF
ON
ON
—
TH2 < – 30°C
Pd 24 kg/cm 2 G
Pd
(2.35 MPa) and
after 30 seconds.
ON when the high
pressure (Pd) ex-
—
ceeds the control
pressure limit.
• Td > 130°C
• Pd > 20 kg/cm
—
Defrost
(4-minute)
–96–
SV4
ON
—
—
—
Normally ON
—
TH2
2
23 kg/cm G Pd 23 kg/cm
(2.26 MPa)
(2.26 MPa) and
after 30 seconds
Pd 20 kg/cm
(1.96 MPa)
and
2
G
Td 115°C
(1.96 MPa)
or
TH2 < – 10°C
Stop
(3-minute)
OFF
– 15°C
2 G
2
G