Mitsubishi Electric CITY MULTI PUHY-400YMF-C Service Handbook page 79

(4) Bypass - capacity control
The solenoid valves have bypass valves (SV1, SV4 and SV6) that allow bypassing of the high pressure and low
pressure sides and solenoid valves (SV22 and SV32) that control the capacity valve inside the compressor. Those
operation are as follows.
Variable Capacity Unit
Constant Capacity Unit
Use
* The compressor of constant capacity unit starts in un-load operation in the initial start mode and during defrosting
only, and starts in full-load operation at all other times by SV22,23 switching.
Normally compressor capacity control is not performed.
1) Bypass Valve (SV6) (SV6 is open when ON, variable capacity unit only)
• The valve is set as follows according to whether the variable capacity unit No. 1 and No. 2 compressors are
operating.
No. 1 Compressor No. 2 Compressor
Stopped
Operating
Operating
SV1
Maintenance of high-pressure/low-pressure,
discharge temperature
SV6
Stopped OFF
Stopped ON
Operating OFF
: Installed
SV4 SV6
-76-
: Not Installed
SV22, SV32
Controls the
compressors'
internal volume
control valve