Lennox International Inc. 10ACB - Manual (Page 10)

3DJH 
4-- Subtract the liquid line temperature from the satu-
ration temperature (according to the chart) to de-
termine subcooling. (Saturation temperature --
Liquid line temperature = Subcooling)
5-- Compare the subcooling value with those in table
5. If subcooling is greater than shown, some refrig-
erant must be recovered. If subcooling is less than
shown, some refrigerant must be added.
TABLE 5
SUBCOOLING FOR RFC SYSTEMS
OUTDOOR
TEMP
LIQUID SUBCOOLING [+ 1-F (.6-C)]
TEMP.
-F (-C) 012 018 024 030 036 042 048 060
60
(16)
14
(7.8)
17
(9.5)
18
(10)
18
(10)
14
(8)
14
(8)
12
(6.7)
14
(8)
65
(18)
13
(7.2)
16
(8.9)
16
(8.9)
17
(9.5)
13
(7.8)
13
(7.8)
11
(6.1)
14
(8)
70
(21)
12
(6.7)
15
(8.3)
14
(7.8)
16
(8.9)
12
(6.7)
13
(7.8)
10
(5.6)
13
(7.8)
75
(24)
10
(5.6)
14
(7.8)
12
(6.7)
15
(8.3)
10
(5.6)
12
(6.7)
9
(5)
13
(7.8)
80
(27)
9
(5)
13
(7.2)
11
(6.1)
14
(8)
9
(5)
11
(6.1)
9
(5)
12
(6.7)
85
(29)
8
(4.5)
12
(6.7)
10
(5.6)
13
(7.8)
8
(4.4)
10
(5.6)
9
(5)
12
(6.7)
90
(32)
7
(3.9)
11
(6.1)
9
(5)
12
(6.7)
7
(3.9)
10
(5.6)
8
(4.5)
12
(6.7)
95
(35)
6
(3.3)
9
(5)
8
(4.5)
11
(6.1)
6
(3.3)
9
(5)
8
(4.5)
12
(6.7)
100
(38)
4
(2.2)
8
(4.5)
7
(3.9)
10
(5.6)
5
(2.8)
9
(5)
8
(4.5)
11
(6.1)
105
(41)
2
(1.1)
7
(3.9)
6
(3.3)
9
(5)
4
(2.2)
9
(5)
7
(3.9)
10
(5.6)
110
(43)
2
(1.1)
6
(3.3)
6
(3.3)
7
(3.9)
3
(1.7)
8
(4.5)
7
(3.9)
9
(5)
115
(45)
1
(0.6)
5
(2.8)
5
(2.8)
5
(2.8)
2
(1.1)
7
(3.9)
6
(3.3)
8
(4.5)
Note -- For best results, the same electronic thermometer should be
used to check both outdoor ambient and liquid temperatures.
&+$5*,1* )25 7;9 6<67(06
Weighing in the Charge
TXV Systems, < 60-F
$-+ Outdoor Temp
1-- Recover the refrigerant from the unit.
2-- Conduct a leak check, then evacuate as previously
outlined.
3-- Weigh in the factory charge as shown on the out-
door unit’s rating plate.
The Approach Method
TXV Systems, > 60-F
$-+ Outdoor Temp
Having taken the outdoor ambient and liquid line tem-
perature readings, subtract the outdoor ambient tem-
perature from the liquid line temperature to determine
the Approach temperature. (Liquid Line -F (-C) -- Out-
door Ambient -F (-C) = Approach Temperature.) The
resulting difference (Approach temperature) should
agree with the values given in table 6. If not, add refrig-
erant to lower the approach temperature or recover re-
frigerant from the system to increase the approach
temperature.
TABLE 6
APPROACH METHOD
MODEL
NO.
APPROACH TEMPERATURE
LIQUID LINE -- OUTDOOR AMBIENT -F (-C)
10ACB12 7 (3.9)
10ACB18 5 (2.8)
10ACB24 9 (5)
10ACB30 10 (5.6)
10ACB36 12 (6.7)
10ACB42 14 (8)
10ACB48 13 (7.2)
10ACB60 12 (6.7)
10ACB62 12 (6.7)
Note -- For best results, the same electronic thermometer should be
used to check both outdoor ambient and liquid temperatures.
6<67(0 23(5$7,21
Condensing unit and indoor blower cycle on demand
from room thermostat. When thermostat blower
switch is switched to ON position, indoor blower oper-
ates continuously.
Crankcase Heater
Three and one-half, four and five ton units are equipped
with internal self-regulating crankcase heaters.
Compressor Start Kit
Three and one-half, four and five ton single-phase units
have internal start components and do not require field
installation of a compressor start kit.
Timed-Off Control (Option Units ONLY)
Option units are factory-equipped with a timed-off
control which helps equalize system pressures that al-
lows the compressor to start in an unloaded condition
as well as preventing compressor short-cycling. The
timed-off control delays compressor start-up for five
minutes on thermostat demand. Mounted in the con-
trol box, the control is wired between thermostat ter-
minal “Y” and the compressor contactor.
High and Low Pressure Switches
(International and Option Units ONLY)
10ACB international and option units are factory-
equipped with both high and low pressure switches.
The pressure switches are located on the valve cores in
the liquid line to allow easy access. The manually reset
high pressure switch protects the system from high
pressure conditions as a result of a fan failure or a