COOLING ONLY PROCEDURE
Units with Cooling Mode TXV
Units installed with cooling mode TXV require charging with the
subcooling method.
1. Operate unit a minimum of 10 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 unit rating plate 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.
Units with Indoor Pistons
Units installed with indoor pistons require charging with the
superheat method.
The following procedure is valid when indoor airflow is within ±
21% of its rated CFM.
1. Operate unit a minimum of 10 minutes before checking
charge.
2. Measure suction pressure by attaching a gage to suction valve
service port.
3. Measure suction temperature by attaching an accurate ther-
mistor type or electronic thermometer to suction line at service
valve.
4. Measure outdoor air dry-bulb temperature with thermometer.
5. Measure indoor air (entering indoor coil) wet-bulb tempera-
ture with a sling psychrometer.
6. Refer to Table 4. Find outdoor temperature and evaporator
entering air wet-bulb temperature. At this intersection, note
superheat.
7. Refer to Table 5. Find superheat temperature located in item 6
and suction pressure. At this intersection, note suction line
temperature.
8. If unit has a higher suction line temperature than charted
temperature, add refrigerant until charted temperature is
reached.
9. If unit has a lower suction line temperature than charted
temperature, reclaim refrigerant until charted temperature is
reached.
10. If outdoor air temperature or pressure at suction valve
changes, charge to new suction line temperature indicated on
chart.
Step 12—Final Checks
IMPORTANT: Before leaving job, be sure to do the following:
1. Securely fasten all panels and covers.
2. Tighten service valve stem caps to 1/12-turn past finger tight.
3. Leave User’s Manual with owner. Explain system operation
and periodic maintenance requirements outlined in manual.
4. Fill out Dealer Installation Checklist and place in customer
file.
CARE AND MAINTENANCE
For continuing high performance and to minimize possible equip-
ment failure, periodic maintenance must be performed on this
equipment.
Frequency of maintenance may vary depending upon geographic
areas, such as coastal applications.
Table 3—Required Liquid-Line Temperature (°F)
LIQUID
PRESSURE AT
SERVICE VALVE
(PSIG)
REQUIRED SUBCOOLING
TEMPERATURE
(°F)
5 101520
134 71 66 61 56
141 74 69 64 59
148 77 72 67 62
156 80 75 70 65
163 83 78 73 68
171 86 81 76 71
179 89 84 79 74
187 92 87 82 77
196 95 90 85 80
205 98 93 88 83
214 101 96 91 86
223 104 99 94 89
233 107 102 97 92
243 110 105 100 95
253 113 108 103 98
264 116 111 106 101
274 119 114 109 104
285 122 117 112 107
297 125 120 115 110
309 128 123 118 113
321 131 126 121 116
331 134 129 124 119
346 137 132 127 122
359 140 135 130 125
6
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