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036-21544-001 Rev. B (1103)
24 Mitsubishi Electronics 2003
SYSTEM CHARGE
The factory charge in the outdoor unit includes enough
charge for the unit and the smallest matched evaporator and
25 feet of line. Some evaporator matches may require some
additional charge. See Tabular Data sheet provided in unit lit-
erature packet.
The “TOTAL SYSTEM CHARGE” must be permanently
stamped on the unit data plate.
Total system charge is determined as follows:
1. Determine outdoor unit charge for the selected evapora-
tor from the corresponding table on Pages 4-6.
2. If using line length other than 25 feet, calculate the line
charge from the tables on Page 24.
NOTE: The line charge over 25 feet should be included on
the data plate and must be added to the system.
3. Total system charge = item 1 + item 2.
4. Permanently stamp the unit data plate with the total
amount of refrigerant in the system.
Use one of the following charging methods whenever addi-
tional refrigerant is required for the system charge.
MEASUREMENT METHOD
If a calibrated charging cylinder or accurate weighing device
is available, add refrigerant accordingly.
SUPERHEAT CHARGING METHOD
NOTE: Use this method only during system maintenance
and repair.
1. Operate system until temperatures and pressures stabi-
lize (minimum of 10 minutes).
2. Measure and record indoor wet bulb (WB) temperature
using a sling psychrometer and the outdoor dry bulb
(DB) temperature using a thermometer.
Refrigerant charging should only be carried out
by a qualified air conditioning contractor.
Compressor damage will occur if system is
improperly charged. On new system installations
charge system per R-22 charge information label
and follow guidelines in this instruction.
Check flare caps on service ports to be sure they
are leak tight. DO NOT OVER TIGHTEN
(between 40 and 60 inch - lbs. maximum).
Table 1: SUPERHEAT VALUE
INDOOR WB
°F
1
OUTDOOR DB°F
55 60 65 70 75 80 85 90 95 100 105 110 115
50 9 7
52 12 10 6
54 14 12 10 7
56 17 15 14 10 6
58 20 18 16 13 9 5
60 23 21 19 16 12 8 6
62 26 24 22 19 16 12 8 5
64 29 27 24 21 18 15 11 9 6
66 32 31 30 24 23 18 15 11 9 6
68 35 33 30 27 24 21 19 16 14 12 9 6
70 35 33 30 28 25 22 20 18 15 13 11 8
72 35 33 30 28 26 24 20 20 17 15 14
74 34 31 30 27 25 23 22 20 18
76 35 33 31 29 27 26 25 23
1. Evaporator Entering Air °F
OPERATING PRESSURES / SUPERHEAT
7