Mitsubishi Electric PUHY-HP120TNU-A, Service Handbook

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[6-3 Evaluating and Adjusting Refrigerant Charge ]
4 -
chapter 6 HWE18240_GB
6 Test Run
6-3-4 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 operation <A> below is followed.
The unit will not go into the refrigerant amount adjust mode when the switch on the OS is set to ON.
Operation <A>
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) Using the flowchart on the next page, adjust the refrigerant charge. Check the TH4, TH3, TH2, TH6, Te, and Tc values of OC,
OS1, and OS2 by setting the diagnostic switch (SW4 (SW6-10: OFF) first, and use these values to diagnose the refrigerant
charge.
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 outdoor unit is 5°C [41°F] or above and SH on the indoor unit is between 5 and 15°C [41 and 59°F].
The refrigerant amount may seem adequate at the moment, but may turn out to be inadequate later on.
TH3-TH6 on the outdoor unit is 5°C [41°F] or less and SH on the indoor unit is 5°C [41°F] or less.
Wait until the TH3-TH6 reaches 5°C [41°F] or above and the SH of the indoor unit is between 5 and 15°C [41 and 59°F] to
determine that the refrigerant amount is adequate.
3) If the high pressure is not at least 2.0 MPa [290 psi], a correct judgment will not be possible for refrigerant adjustment. Perform
the adjustment when the outdoor air temperature is at least 20°C [68°F].
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.
SW4 settings
Self-diagnosis swithes on TH4
Self-diagnosis swithes on TH2 Self-diagnosis swithes on TH6
Self-diagnosis swithes on TH3
Self-diagnosis swithes on Tc Self-diagnosis swithes on Te
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
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
The figure at left shows that the switches 1 through 5 are set to ON and 6 through 10 are set to OFF.