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Attach the manifold center port hose to a nitrogen cylin-
der with pressure regulator set to 150 psig (1034 kPa)
and purge the hose. Open the manifold gauge valves
to break the vacuum in the line set and indoor unit.
Close the manifold gauge valves.
WARNING
Danger of Equipment Damage.
Avoid deep vacuum operation. Do not use com-
pressors to evacuate a system.
Extremely low vacuums can cause internal arcing
and compressor failure.
Damage caused by deep vacuum operation will
void warranty.
7 − Shut off the nitrogen cylinder and remove the manifold
gauge hose from the cylinder. Open the manifold
gauge valves to release the nitrogen from the line set
and indoor unit.
8 − Reconnect the manifold gauge to the vacuum pump,
turn the pump on, and continue to evacuate the line set
and indoor unit until the absolute pressure does not
rise above 500 microns (29.9 inches of mercury) within
a 20−minute period after shutting off the vacuum pump
and closing the manifold gauge valves.
9 − When the absolute pressure requirement above has
been met, disconnect the manifold hose from the vacu-
um pump and connect it to an upright cylinder of R−410A
refrigerant. Open the manifold gauge valves to break
the vacuum from 1 to 2 psig positive pressure in the line
set and indoor unit. Close manifold gauge valves and
shut off the R−410A cylinder and remove the manifold
gauge set.
C−Charging
This system is charged with R−410A refrigerant which op-
erates at much higher pressures than R22. The check/ex-
pansion valve provided with the unit is approved for use
with R−410A. Do not replace it with a valve designed for use
with R22. This unit is NOT approved for use with coils which
include metering orifices or capillary tubes.
Processing Procedure
The unit is factory−charged with the amount of R−410A re-
frigerant indicated on the unit rating plate. This charge is
based on a matching indoor coil and outdoor coil with a 15
foot (4.6m) line set. For varying lengths of line set, refer to
table 8 for refrigerant charge adjustment. .
IMPORTANT
Mineral oils are not compatible with R−410A. If oil
must be added, it must be a polyol ester oil.
It is desirable to charge the system in the cooling cycle if
weather conditions permit. However, if the unit must be
charged in the heating season, one of the following proce-
dures must be followed to ensure proper system charge.
Weighing in the Charge TXV Systems –
Outdoor Temp. < 65
F (18
C)
If the system is void of refrigerant, or if the outdoor ambient
temperature is cool, the refrigerant charge should be
weighed into the unit. Do this after any leaks have been re-
paired.
1 − Recover the refrigerant from the unit.
2 − Conduct a leak check, then evacuate as previously
outlined.
3 − Weigh in the unit nameplate charge.
If weighing facilities are not available or if you are charging
the unit during warm weather, follow one of the other proce-
dures outlined below.
Subcooling Method
Outdoor Temp. < 65°F (18°C)
When the outdoor ambient temperature is below 65°F
(18°C), use the subcooling method to charge the unit. It
may be necessary to restrict the air flow through the out-
door coil to achieve pressures in the 325−375 psig
(2240−2585 kPa) range. These higher pressures are nec-
essary for checking the charge. Block equal sections of air
intake panels and move obstructions sideways until the liq-
uid pressure is in the 325−375 psig (2240−2585 kPa) range.
Figure 20 shows a four sided unit for example..
Blocking Outdoor Coil
cardboard or
plastic sheet
Outdoor coil should be
blocked one side
at a time with cardboard
or plastic sheet until proper
testing pressures
are reached.
FIGURE 20
1 − With the manifold gauge hose still on the liquid service
port and the unit operating stably, use a digital ther-
mometer to record the liquid line temperature.
2 − At the same time, record the liquid line pressure reading.
3 − Use a temperature/pressure chart for R−410A to deter-
mine the saturation temperature for the liquid line pres-
sure reading. See table 13.
4 − Subtract the liquid line temperature from the saturation
temperature (according to the chart) to determine sub-
cooling.
(Saturation temperature − Liquid line tem-
perature = Subcooling)
5 − Compare the subcooling value with those in table 9. If
subcooling is greater than shown, recover some refrig-
erant. If subcooling is less than shown, add some re-
frigerant. Be aware of the R−410A refrigerant cylinder.
It will be light maroon−colored. Refrigerant should be
added through the vapor line valve in the liquid state.
Some R−410A cylinders are equipped with a dip
tube that allows you to draw liquid refrigerant from
the bottom of the cylinder without turning the cyl-
inder upside−down. The cylinder will be marked if it
is equipped with a dip tube.
