Carrier WEATHERMAKERTM TWO-SPEED 38TDB User Manual
Page 11
Step 11—Check Charge
Service valve gage ports are not equipped with Schrader
valves. To prevent personal injury, make sure gage manifold
is connected to the valve gage ports before moving valves off
fully back seated position. Wear safety glasses and gloves
when handling refrigerant.
UNIT CHARGE
Factory charge and charging method are shown on pink charging
label. With unit operating, charge Puron® units with liquid using
a commercial type metering device in manifold hose. Charge
refrigerant into suction line.
NOTE:
Unit is to be charged in high capacity only. Charging in
low capacity may cause compressor chattering and possible
damage to the compressor.
NOTE:
If subcooling charging conditions are not favorable,
charge must be weighed in accordance with unit rating plate ± 0.6
oz/ft of 3/8-in. liquid line above or below 15 ft respectively.
EXAMPLE: To calculate additional charge required for a 25-ft
line set: 25 ft - 15 ft = 10 ft X 0.6 oz/ft = 6 oz of additional charge.
COOLING ONLY PROCEDURE
1. Operate unit a minimum of 15 minutes before checking
charge.
2. Measure liquid service valve pressure by attaching an accurate
gage to service port.
3. Measure liquid line temperature by attaching an accurate
thermistor type or electronic thermometer to liquid line near
outdoor coil.
4. Refer to Table 4 for required subcooling temperature.
5. Refer to Table 3. Find the point where required subcooling
temperature intersects measured liquid service valve pressure.
6. To obtain required subcooling temperature at a specific liquid
line pressure, add refrigerant if liquid line temperature is
higher than indicated or reclaim refrigerant if temperature is
lower. Allow a tolerance of ± 3°F.
.
UNIT CHARGE
Factory charge and charging method are shown on pink charging
label. Puron® refrigerant cylinders contain a dip tube which
allows liquid refrigerant to flow from cylinder in upright
position. Charge Puron units with cylinder in upright position and
a commercial type metering device in manifold hose. Charge
refrigerant into suction line.
NOTE:
Unit is to be charged in high capacity only. Charging in
low capacity may cause compressor chattering and possible
damage to the compressor.
NOTE:
If subcooling charging conditions are not favorable,
charge must be weighed in accordance with unit rating plate ± 0.6
oz/ft of 3/8-in. liquid line above or below 15 ft respectively.
EXAMPLE: To calculate additional charge required for a 25 ft line
set: 25 ft - 15 ft = 10 ft x 0.6 oz/ft = 6 oz of additional charge.
Step 12—System Functions and Sequence of Operation
The outdoor unit control system has special functions. The
following is an overview of the two-speed control functions:
COOLING OPERATION
This product utilizes a 2-stage cooling indoor thermostat. With a
call for first stage cooling (Yl), the outdoor fan and low capacity
compressor are energized. If low capacity cannot satisfy cooling
demand, high capacity is energized (Yl and Y2 or Y2 only) by the
second stage of indoor thermostat. After second stage is satisfied,
the unit returns to low-speed operation until first stage is satisfied
or until second stage is required again. When both first stage and
second stage cooling are satisfied, the compressor will shut off.
NOTE:
If unit has not operated within the past 12 hr, or following
a unit power-up, upon the next thermostat high- or low-speed
demand, unit operates for a minimum of 5 minutes on high-speed.
NOTE:
When two-speed unit is operating at low speed, system
vapor (suction) pressure will be higher than a standard single-
speed system or high-speed operation.
NOTE:
Outdoor fan motor will continue to operate for one
minute after compressor shuts off, when outdoor ambient is greater
than or equal to 100°F.
STATUS FUNCTION LIGHTS
A system control STATUS function light is located on the outdoor
unit control board. (See Fig. 12.) The STATUS light provides
indication signals for several system operations. See Table 5 for
codes and definitions. Table 5 also provides the order of signal
importance.
NOTE:
Only one code will be displayed on the outdoor unit
control board (the most recent, with the highest priority).
Table 3—Required Liquid-Line Temperature (°F)
LIQUID
PRESSURE AT
SERVICE VALVE
(PSIG)
REQUIRED SUBCOOLING
TEMPERATURE
(°F)
8
12
14
16
18
18
189
58
56
54
52
50
48
195
60
58
56
54
52404
50
202
62
60
58
56
54
52
208
64
62
60
58
56
54
215
66
64
62
60
58
56
222
68
66
64
62
60
58
229
70
68
66
64
62
60
236
72
70
68
66
64
62
243
74
72
70
68
66
64
251
76
74
72
70
68
66
259
78
76
74
72
70
68
266
80
78
76
74
72
70
274
82
80
78
76
74
72
283
84
82
80
78
76
74
291
86
84
82
80
78
76
299
88
86
84
82
80
78
308
90
88
86
84
82
80
317
92
90
88
86
84
82
326
94
92
90
88
86
84
335
96
94
92
90
88
86
345
98
96
94
92
90
88
354
100
98
96
94
92
90
364
102
100
98
96
94
92
374
104
102
100
98
96
94
384
106
104
102
100
98
96
395
108
106
104
102
100
98
406
110
108
106
104
102
100
416
112
110
108
106
104
102
427
114
112
110
108
106
104
439
116
114
112
110
108
106
450
118
116
114
112
110
108
462
120
118
116
114
112
110
474
122
120
118
116
114
112
486
124
122
120
118
116
114
499
126
124
122
120
118
116
511
128
126
124
122
120
118
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