Mitsubishi Electric PUHY-HP144TSHMU-A Service Handbook page 98

[ VII Control ]
-10- Linear expansion valve control
Linear expansion valve performs in each operation mode as shown in the table below.
Refrigerant flow amount to the injection is controlled by intermediate pressure control or compressor discharge superheat con-
trol.
Linear expansion valve
LEV1
LEV2a,LEV2b
LEV4
If outdoor temperature (TH7) is between 3°C[37°F] and 5°C[41°F] during heating operation, either 5°C[41°F] and above per-
formance or 3°C[37°F] or below performance based on the table above starts.
Linear expansion valve performs as shown in the table below while the compressor is stopped or during Thermo-OFF
Linear expansion valve
LEV1
LEV2a,LEV2b
LEV4
(1) Subcool coil control
Subcool coil is performed individually on the OC and OS.
Subcool amount at the heat exchanger outlet of the outdoor unit calculated by high pressure (63HS1) and liquid pipe temper-
ature (TH3) or superheat amount calculated by low pressure (63LS) and subcool coil bypass outlet temperature (TH2) is ad-
justed to be in the certain range every 30 seconds.
Valve opening is corrected based on the subcool coil inlet/outlet temperature (TH3, TH6), high pressure (63HS1), and dis-
charge temperature (TH4).
(2) Compressor discharge superheat control
Compressor discharge superheat is performed individually on the OC and OS.
Compressor discharge superheat control adjusts compressor discharge superheat that is calculated by compressor dis-
charge temperature (TH4) and high pressure (63HS1) to be in the certain range as shown in the table below every 30 seconds.
Compressor frequency
93Hz min
83 - 92Hz
72 - 82Hz
71Hz max
(3) Intermediate pressure control
OC interlocks with OS and performs intermediate pressure control. However, valve opening of OC and OS differs depending
on refrigerant amount of each outdoor unit.
Intermediate pressure control adjusts intermediate pressure of OC (HPS2) to be in the certain range (target: 1.3 MPa [189
psi]) every 30 seconds.
HWE0716A
During cooling operation
Subcool coil control
Fully open (1400) Intermediate pressure control
Fully closed (0)
While compressor is stopped
65
200 or 1400
Fully closed (0)
Compressor discharge superheat target value
- 89 -
During heating operation
Outdoor temperature
5°C[41°F] and above
Fully closed (0)
Intermediate pressure control
Fully closed (0)
Cooling Thermo-OFF
From 0 to 65 in 3 minutes
(stays 0 while other out-
door units are in operation)
60 or 130
Fully closed (0)
20
25
30
50
Outdoor temperature
3°C[37°F] or below
Compressor discharge
superheat control
Fully closed (460)
Heating Thermo-OFF
From 0 to 65 in 3 minutes
(stays 0 while other out-
door units are in operation)
60
Fully closed (0)
GB