Page 10
Weighing in the Charge Fixed Orifice or
TXV Systems – Outdoor Temp < 60_F (16_C)
If the system is void of refrigerant, or if the outdoor ambient
temperature is cool, the refrigerant charge should be
weighed into the unit according to the total amount shown
on the unit nameplate. This may be done after any leaks
have been repaired. If weighing facilities are not available
or if unit is being charged during warm weather, follow one
of the other procedures outlined below.
1 - Recover the refrigerant from the unit.
2 - Conduct a leak check, then evacuate as previously
outlined.
3 - Weigh in the factory charge according to the amount
recorded on the outdoor unit nameplate.
Charging Using the Subcooling Method
Fixed Orifice Systems – Outdoor Temp.
> 65_F (18_C)
If you charge afixed orifice system whenthe outdoor ambi-
ent is 65_F (18_C) or above, use the subcooling method to
charge the unit.
1 - With the manifold gauge hose still on the liquid service
port and the unit operating stably, use a digital ther-
mometer to record the liquid line temperature.
2 - At the same time, record the liquid line pressure reading.
3 - Use a temperature/pressure chart for HCFC-22 to de-
termine the saturation temperature for the liquid line
pressure reading.
4 - Subtract the liquidline temperature fromthe saturation
temperature (according to the chart) to determine sub-
cooling. (Saturation temperature - Liquid line tem-
perature = Subcooling)
5 - Compare the subcooling value with those in table 3. If
subcooling is greater than shown, some refrigerant
must be recovered. If subcooling is less than shown,
some refrigerant must be added.
Table 3
10ACC Subcooling Values
(Fixed Orifice Systems Only)
OUTDOOR
LIQUID SUBCOOLING [+ 1_F (.6_C)]
_F (_C)
18 24 30 36 42 48 60
65
(18)
13
(7)
14
(8)
14
(8)
17
(9.5)
17
(9.5)
15
(8.3)
14
(8)
70
(21)
13
(7)
14
(8)
14
(8)
17
(9.5)
17
(9.5)
14
(8)
15
(8.3)
75
(24)
13
(7)
13
(7)
13
(7)
16
(9)
16
(9)
13
(7)
15
(8.3)
80
(27)
12
(6.7)
13
(7)
13
(7)
15
(8.3)
15
(8.3)
13
(7)
14
(8)
85
(29)
12
(6.7)
12
(6.7)
13
(7.8)
14
(8)
14
(8)
12
(6.7)
14
(8)
90
(32)
11
(6)
12
(6.7)
12
(6.7)
14
(8)
14
(8)
12
(6.7)
13
(7)
95
(35)
10
(5.6)
11
(6)
11
(6)
12
(6.7)
14
(8)
12
(6.7)
13
(7)
100
(38)
9
(5)
9
(5)
10
(5.6)
11
(6)
13
(7)
11
(6)
12
(6.7)
105
(41)
8
(4.5)
8
(4.5)
9
(5)
10
(5.6)
12
(6.7)
10
(5.6)
12
(6.7)
110
(43)
7
(4)
7
(4)
7
(4)
9
(5)
11
(6)
9
(5)
11
(6)
115
(45)
7
(4)
6
(3.3)
6
(3.3)
8
(4.5)
11
(6)
8
(4.5)
10
(5.6)
Charging Using the Approach Method
TXV Systems -- Outdoor Temp. > 60_F (16_C)
When an expansion valve system is being charged when
the outdoor ambient temperature is 60_F (16_C) or above,
it is best to charge the unit using the approach method.
Subtract the outdoor ambient temperature from the liquid
line temperature to determine the Approach temperature.
(Liquid Line _F (_C) - Outdoor Ambient _F (_C) = Ap-
proach Temperature.) The resulting difference (Ap-
proach temperature) should agree with the values given in
table 4. If not, add refrigerant to lower the approach tem-
perature or recover refrigerant from the system to increase
the approach temperature.
Table 4
Approach Method
Model No.
Approach Temperature
Liquid Line - Outdoor Ambient _F (_C)
10ACC-018 7 (4)
10ACC-024 9 (5)
10ACC-030 12 (6.7)
10ACC-036 11 (6)
10ACC-042 13 (7)
10ACC-048 8 (4.5)
10ACC-060 13 (7)
NOTE - For best results, use the same digital thermometer to check both
outdoor ambient and liquid temperatures.
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