Refrigerant Bypass Control - Mitsubishi Electric PURY-M200YNW-A1 Service Handbook

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