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507043-04C
mrcool.com
6. Measure indoor air (entering indoor coil) wet-bulb
temperature with a sling psychrometer.
7. Compare superheat reading at service valve with the
chart located on control box cover.
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. Remove charge if superheat is low and add charge if
superheat is high.
Units with Indoor 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. Determine saturation
temp. from T/P chart.
3. Measure liquid line temperature by attaching an
accurate thermistor type or electronic thermometer to
liquid line near outdoor coil.
4. Calculate subcooling (saturation temp. - measured
temp.) and compare to table on back of control box
cover.
5. Add refrigerant if subcooling is lower than range shown
in table. Recover refrigerant to decrease subcooling.
6. If ambient temp. is lower than 65° F, weigh refrigerant
according to the name plate data.
NOTE: If a TXV is installed on indoor unit, a hard start kit will
be required on all models with reciprocating compressors.
are also recommended for areas with utility power lower
than 208 Vac.
System Operation
The outdoor unit and indoor blower cycle on demand
from the room thermostat. When the thermostat blower
switch is in the ON position, the indoor blower operates
continuously.