Mitsubishi Electric PUHY-P120YHMU-A, Service Manual

Page: 129 / 326

[
VIII
Test Run Mode ]
- 120 - HWE0804A GB
[5] Refrigerant Amount Adjust Mode
1. Procedures
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 outdoor 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 values of TH4, TH3, TH6, and Tc, following the flowchart below. Check the TH4,
TH3, TH6, and Tc values on the OC, OS1, and OS2 by following the flowchart. The TH4, TH3, TH6, and Tc values can be
displayed by setting the self-diagnosis switch (SW1) on the main board on the OC, OS1, and OS2.
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.
TH3-TH6 on the indoor unit 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.
TH3-TH6 on the indoor unit is 5°C [9°F] or less and SH on the indoor unit is 5°C [9°F] or less.
Wait until the TH3-TH6 reaches 5°C [9°F] or above and the SH of the indoor unit is between 5 and 15°C [9 and 27°F] to
determine that the refrigerant amount is adequate.
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 TH6
Self-diagnosis swithes on TH3
Self-diagnosis swithes on Tc
1 2 3 4 5 6 7 8 9 10
ON
1 2 3 4 5 6 7 8 9 10
ON
1 2 3 4 5 6 7 8 9 10
ON
1 2 3 4 5 6 7 8 9 10
ON