Mitsubishi Electric CITY MULTI PUHY-P400YEM-A Service Handbook page 97

<Constant Capacity Unit>
Item
At compressor is started
After thermostat reset or 3
minutes after startup
Compressor stopped during
cooling or heating mode
After operation has been stopped
During defrosting (( 1) in Fig
below)
When low pressure (63LS) has
dropped
When the high pressure (Pd) is
risen up
When the discharge temperature
(Td) is risen up.
When the high pressure (Pd) is
fallen up.
Example of SV1 operation
Compressor
Bypass
solenoid
Start
Thermo.
valve (SV1)
OFF
(4-minute)
3) Capacity control solenoid valve (SV22, SV32) Model 500 only.
• Operation of solenoid valve
Solenoid valve
Coil
Status
Full-load
(Operating at 100 %
OFF
capacity)
Un-load
(Capacity control ON
operation)
• SV22 and SV32 stand for SV2 and SV3 of the No. 2
compressor.
SV1
ON
ON for 4 minutes
ON for 4 minutes
ON for 3 minutes
ON for 3 minutes
ON during normal operation
Low pressure
(63LS) 0.098 MPa
Pd 2.55 MPa
When the discharge
temperature 130˚ C
and high pressure
(Pd)
1.96 MPa
or lo w
pressure (63LS)
0.245 MPa.
—
Thermo.
ON
(3-minute) (4-minute)
SV22 SV32
Valve Coil Valve
Open OFF Closed
Closed ON Open
OFF
Low pressure
(63LS) 0.147 MPa
2.25 MPa
Pd
and
after 30 seconds
When the dis-
charge tempera-
ture 115˚C
In heating mode, at starting
and low volume of indoor
unit, if high pressure (Pd)
1.18 MPa and
low pressure saturation
temperature (ET) – 20˚C
Defrost
( 1)
(4-minute)
-94-
SV4
ON OFF
—
—
—
—
—
— —
— —
— —
When the high
pressure (Pd)
1.27 MPa and
after 30 minutes of
operation.
Stop
(3-minute)
SV22
SV32
COMP