Mitsubishi Electric City Multi PUHY-HP144TSHMU-A, Service Handbook

Page: 93 / 265

[
VII
Control ]
- 84 - HWE0716A GB
-5- Bypass Control
Solenoid valves are categorized into 3 types: High/low pressure bypass valve (SV1a), High/low pressure bypass valve via
heat exchanger (SV9), and circuit switch valve at subcool coil low pressure side (SV6). Refer to the following tables for each
valve operation.
(1) Bypass solenoid valve (SV1a) (ON = Open)
(2) Bypass solenoid valve (SV2) (ON = Closed)
Operation
SV1a
ON OFF
At NO1 compressor startup (outdoor tem-
perature: -15°C[5°F] or more) or at NO2
compressor startup (HP144/HP192 models) ON for 4 minutes.
After resuming operation after the comple-
tion of the defrost cycle ON for 8 minutes.
After NO1 compressor startup (outdoor tem-
perature: -15°C[5°F] or lower) or after re-
suming operation after the completion of the
defrost cycle (outdoor temperature:
-15°C[5°F] or lower) ON when 25 minutes or less have
passed and 63HS1 or 2 < 1.96MPa
[284 psi]. OFF when 25 minutes or more
have passed or 63HS1 or 2
1.96MPa [284 psi].
After resuming operation after Themo mode
or after 3-minute restart delay mode ON for 4 minutes.
When the compressor stops at cooling/heat-
ing mode Always ON.
Exception: OFF when 63HS1 or 2 -63LS is 0.2 MPa [29 psi] or less
After the operation has stopped ON for 3 minutes.
Exception: OFF when 63HS1 or 2 -63LS is 0.2 MPa [29 psi] or less
During defrost cycle ON
During oil recovery operation OFF during oil recovery operation (cooling/heating) after low frequency
continuous operation.
During cooling operation, during compres-
sor frequency Fmin operation, or when low
pressure (63LS) drops (3 minutes have
passed since startup) When low pressure (63LS) drops
below 0.23 MPa [33 psi]. When low pressure (63LS) rises
above 0.38MPa [55 psi].
During heating operation and when low
pressure (63LS) drops (3 minutes have
passed since start up and resuming opera-
tion after the completion of the defrost cycle
.) When low pressure (63LS) drops
below 0.12 MPa [17 psi]. 3 minutes have passed since ON
control started, and when low pres-
sure (63LS) drops below 0.16MPa
[23 psi].
When high pressure (63HS1 or 2) rises When 63HS1, 63HS2 exceeds
3.62 MPa [525 psi]. When 63HS1, 62HS2 are or below
3.43 MPa [497 psi] and 30 seconds
have passed.
Operation
SV2
ON OFF
At NO1 compressor startup (outdoor tem-
perature: 5°C[41°F] or lower) or after resum-
ing operation after the completion of the
defrost cycle ON when 5 minutes or less have
passed and 63HS1 < 1.96MPa
[284 psi]. OFF when 5 minutes or more have
passed or 63HS1
1.96MPa [284
psi].