Mitsubishi Electric CITY MULTI PUHY-400YMF-B, Service Handbook, Page: 87 / 204

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(10) Liquid Distribution Control (electronic expansion valve (LEV2) constant capacity unit only)
• Liquid distribution control refers to the process by which liquid refrigerant returning from the constant and variable
capacity units during heating is equally distributed, and the opening of the constant capacity unit LEV2 is adjusted
so that there is no deficiency of liquid refrigerant in the accumulator of each unit.
1
Distribution occurs during heating operations when both the variable and constant capacity units are in operation.
When the constant capacity unit is stopped, the LEV2 opening = 60.
2 The LEV2 opening is set to a standard which varies depending on the current operation frequency.
3
The levels of the superheating level (SH1) of the variable capacity unit temperature A and TH10 (whichever
temperature is higher) and the accumulator liquid level (AL1) are compared to the superheating level (SH2) of the
constant capacity unit temperature A and TH10a and the accumulator liquid level (AL2) to correct the standard
opening of the LEV2 in
2
above.
Chart: Corrections to the Standard LEV2 Opening
Constant Capacity Unit
Superheating Level SH2 > 7 SH2 7
Accumulator Level AL = 0 or 1 AL = 2 AL = 0 or 1 AL = 2
Variable
SH1 > 7
AL = 0 or 1 no change opening down
Capacity Unit
AL = 2 no change opening up no change
SH1 7
AL = 0 or 1 opening up opening down no change opening down
AL = 2 no change opening up no change
* Even when the constant capacity unit is stopped, the after-mentioned liquid refrigerant correction control operation may
control LEV2 operations. After the power source has been turned on, and before the variable capacity unit compressor
begins operation, the LEV2 is opened to 200. (After compressor operation begins, LEV2 = 60)
60 200 2000
Standard LEV2 Opening
Range of Corrections to LEV2 Opening
* Temperature A: low pressure saturation temperature.