Control During Low Outdoor Air Temperature Cooling - Panasonic Urban Multi MX1R Series Service Manual

Function
1.14

Control During Low Outdoor Air Temperature Cooling

When the outdoor air temperature is low in cooling operation, outdoor unit fans, electronic expansion valve
and compressors are controlled as follows in order to primarily maintain high pressure and to protect drop
in refrigerant circulation caused by drop in high pressure.
CU-5
Operating status
Normal operation
Low outdoor temperature
cooling operation
CU-8·10
Operating status
Normal operation
Low outdoor temperature
cooling operation
Note: Step No. changes according to high pressure, low pressure and frequency.
(Step No. increases with reduction of high and low pressure.)
Low Outdoor Air Cooling in Conditions (Steps 1-1, 2, 3)
Conditions satisfied
• Compressor off
or
• Other than cooling
(includes oil return)
or
• High pressure < 22 kg/cm²
(2.156 MPa)
258
Electronic expansion valve
Step 1
Step 2
Electronic expansion valve
Step 1-1
Step 1-2
Step 1-3
Step 2
Normal operation
• Cooling with compressor running
«
(doesn't include oil return)
&
• High pressure < 10 kg/cm² (0.98MPa)
Step 1-1
« carried out 30
continuous
seconds
Step 1-2
« carried out 30
continuous
seconds
Step 1-3
Fan
Fully open H
Fully open L
Fully open OFF
Fan
M1F M2F
Fully open H ON
Fully open L ON
Fully open H OFF
Fully open L OFF
Fully open OFF OFF
¥
• EV = 2000 pulses
• High pressure > 15.2 kg/cm²
¥ carried out 30
continuous
seconds
¥ carried out 30
continuous
seconds
Function Urban Multi "MX1R, ME1R Series" Using R-407C
PACD011001C2
Frequency (Hz)
Changes according to operating
status
76
48
Frequency (Hz)
8K 10K
Changes according to operating
status
96 116
86 106
76 96
62 76
(completely open)
or
(1.489 MPa)
(M017)