Mitsubishi Electric City Multi PURY-EM200YNW-A1, Service Handbook

Page: 143 / 503

[5-2 Outdoor Unit Control ]
12
- chapter 5 BS_05_M
5
Cont
rol
5-2-4 Refrigerant Bypass Control
Bypass solenoid valves, which bypass the high- and low- pressure sides, perform the following functions.
(1) Bypass solenoid valve (SV1a) (ON = Open)
(2) Bypass solenoid valve (SV2) (ON = Open)
(3) Bypass LEV (LEV9)
Operation
SV1a
ON OFF
When starting-up the compressor of each
outdoor unit
ON for 4 minutes.
After the restoration of thermo or 3 minutes
after restart
ON for 4 minutes.
During cooling or heating operation with the
compressor stopped
Always ON.
Exception: OFF when 63HS1-63LS is 0.2MPa[29psi] or less
After the operation has stopped ON for 3 minutes.
Exception: OFF when 63HS1-63LS is 0.2MPa[29psi] or less
During defrost operation ON
While the compressor is operating at the
minimum frequency and when the low pres-
sure (63LS) drops (3 or more minutes after
compressor startup)
When the low pressure (63LS)
drops below 0.23 Mpa [33 psi]
during cooling-only or cooling-main
operation.
When the low pressure (63LS)
drops below 0.38 Mpa [55 psi]
during cooling-only or cooling-main
operation.
When high pressure (63HS1) rises When 63HS1 exceeds
3.62MPa[525psi]
When 63HS1 is 3.43MPa [497 psi]
or below in 30 seconds
Operation
SV2
ON OFF
When high pressure (63HS1) rises during
heating operation
While the compressor is operating
at the minimum frequency and
when 63HS1 exceeds 3.43 MPa
[497 psi] during heating-only or
heating-main operation
When 63HS is 2.65 MPa [384 psi]
or below
When low pressure (63LS) drops during
heating operation
When 63HS is below 1.47 MPa
[213 psi] and 63LS is below 0.25
MPa [36 psi]
When 63HS is above 1.72 MPa
[249 psi] or 63LS is above 0.39
MPa [56 psi]
When the defrost operation is completed SW4(956)=OFF Always ON
SW4(956)=ON ON for 5 minutes
Others Always OFF (Closed)
Operation
LEV9
480 pulses Normal control
When high pressure (63HS1) rises during
heating operation
 SW(876) = ON
While the compressor is operating
at the minimum frequency and
when 63HS1 exceeds 3.43 MPa
[497 psi] during heating-only or
heating-main operation
When 63HS is 2.65 MPa [384 psi]
or below
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