Mitsubishi Electric PQHY-P120THMU-A, Service Handbook

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VIII
Test Run Mode ]
- 184 - HWE09080 GB
2. Procedures <PQRY>
Follow the procedures below to add or extract refrigerant as necessary depending on the operation mode.
When the function switch (SW4-3) on the main board on the heat source unit (OC only) is turned to ON, the unit goes into the
refrigerant amount adjust mode, and the following sequence is followed.
SW4-3 on the OS is invalid, and the unit will not go into the refrigerant amount adjust mode.
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 TH4 value, following the flowchart below. Check the TH4, SC11, SC16, and Tc
values on the OC, OS by following the flowchart. The TH4, SC11, and SC16 values can be displayed by setting the self-diag-
nosis switch (SW1) on the main board on the OC, 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.
Œ
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-
3 and turning them back on, the unit will go back into the refrigerant amount adjust mode.
Self-diagnosis swithes on TH4
Self-diagnosis swithes on SC16
Use these switches to check the TH4, SC11, and SC16.
Self-diagnosis swithes on SC11
ON ON
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
ON