Follow these steps to properly start up the system.
1. Fully back seat (open) liquid- and vapor-tube service valves.
2. Unit is shipped with valve stem(s) front seated (closed) and
caps installed. Replace stem caps after system is opened to
refrigerant flow. Replace caps finger-tight and tighten with
wrench an additional 1/12 turn for back-seating valves (male
square stem).
3. Close electrical disconnects to energize system.
4. Set room thermostat at desired temperature. Be sure set point
is below indoor ambient temperature.
5. Set room thermostat to COOL and fan control to ON or AUTO
mode, as desired. Operate unit for 15 minutes. Check system-
refrigerant charge.
SEQUENCE OF OPERATION
Turn on power to indoor and outdoor units. Transformer is
energized.
On a call for cooling, thermostat makes circuits R-Y and R-G. On
three phase models with scroll compressors, the units are equipped
with a phase monitor to detect if the incoming power is correctly
phased for compressor operation. If the phasing is correct, circuit
R-Y energizes contactor, starting outdoor fan motor and compres-
sor circuit. R-G energizes indoor unit blower relay, starting indoor
blower motor on high speed.
NOTE: If the phasing is incorrect, the contactor will not be
energized. To correct the phasing, interchange any two of the three
power connections on the field side.
When thermostat is satisfied, its contacts open, de-energizing
contactor and blower relay. Compressor and motors stop.
If indoor unit is equipped with an off-delay circuit, the indoor
blower can run up to an additional 120 sec to increase system
efficiency.
Step 11—Check Charge
UNIT CHARGE
Factory charge is shown on unit-rating plate. Adjust charge by
following procedure shown on charging tables located on unit.
NOTE: If superheat- or 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=6ozofadditional charge
COOLING-ONLY PROCEDURE
Units with Cooling Mode TXV
Unit 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 4. Find 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.
Fig. 6—Phase Monitor Control
A00010
Table 3—Phase Monitor LED Indicators
LED STATUS
OFF No call for compressor operation
FLASHING Reversed phase
ON Normal
Table 4—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
5
→
→
→
→
To Next Page
Loading...
