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Refrigerant Charge Adjustment Mode - Mitsubishi Electric PURY-HP72 Service Handbook

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[6-9 Evaluating and Adjusting Refrigerant Charge ]
6-9-4

Refrigerant Charge Adjustment Mode

Follow the procedures below to add or extract refrigerant as necessary depending on the operation mode.
When the function switch (SW4 (922)) on the main board on the outdoor unit (OC only) is turned to ON, the unit goes into the
refrigerant amount adjust mode, and the following sequence is followed.
The unit will not go into the refrigerant amount adjust mode when the switch on the OS is set to ON.
Operation
When the unit is in the refrigerant amount adjust mode, the LEV on the indoor unit does not open as fully as it nor-
mally does during cooling operation to secure subcooling.
1) Adjust the refrigerant amount based on the values of TH4, SC11, SC16, and Tc, following the flowchart below. The TH4,
SC11, SC16, and Tc values can be displayed by using the self-diagnosis switch (SW4 (SW6-10: OFF)) on the control board
of the OC or OS.
2) There may be cases when the refrigerant amount may seem adequate for a short while after starting the unit in the refrigerant
amount adjust mode but turn out to be inadequate later on (when the refrigerant system stabilizes).
When the amount of refrigerant is truly adequate.
Subcool (SC11 and SC16) of the BC controller is 5°C [9°F] or above and SH on the indoor unit is between 5 and 15°C [9 and
27°F].
The refrigerant amount may seem adequate at the moment, but may turn out to be inadequate later on.
Subcool (SC11 and SC16) of the BC controller is 5°C [9°F] or less and SH on the indoor unit is 5°C [9°F] or less.
Wait until the Subcool (SC11 and SC16) of the BC controller reaches 5°C [9°F] or above and the SH of the indoor unit is be-
tween 5 and 15°C [9 and 27°F] to determine that the refrigerant amount is adequate.
SC11: Subcool of liquid refrigerant at BC controller inlet; SC16: Subcool of liquid refrigerant at BC controller outlet
3) High pressure must be at least 2.0MPa [290psi] to enable a proper adjustment of refrigerant amount to be made.
4) Refrigerant amount adjust mode automatically ends 90 minutes after beginning. When this happens, by turning off the SW4
(922) and turning them back on, the unit will go back into the refrigerant amount adjust mode.
For how to read the SW settings, refer to the following page(s). [9-1-1 How to Read the LED](page 325)
HWE13080
Self-diagnosis swithes on TH4
1 2 3 4 5
6
7 8 9 10
ON
Self-diagnosis swithes on SC16
1 2 3 4 5
6
7 8 9 10
ON
Use these switches to check the TH4, SC11, and SC16.
Self-diagnosis swithes on SC11
1 2 3 4 5
6
7 8 9 10
ON
- 164 -
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