506762-01
Page 13 of 24
Issue 1143
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Low pressure gauge to suction line service valve
•
High pressure gauge to liquid line service valve
2.
Close manifold gauge set valves. Connect the center
manifold hose to an upright cylinder of R-410A.
3.
If room temperature is below 70° F, set the room thermostat
to call for heat. This will create the necessary load for
properly charging the system in the cooling cycle.
4.
Use a digital thermometer to record the outdoor ambient
temperature.
5.
When the heating demand has been satisfied, switch
the thermostat to cooling mode with a set point of 68° F.
When pressures have stabilized, use a digital
thermometer to record the liquid and suction line
temperatures.
6.
The outdoor temperature will determine which charging
method to use. Proceed with the appropriate charging
method.
Charge Using Weigh-In Method (Fixed Orifice/TXV
Systems)
If the system is void of refrigerant, or if the outdoor ambient
temperature is cool, first locate and repair any leaks then
use the weigh-in method to charge the unit.
1.
Recover the refrigerant from the unit.
2.
Conduct a leak check, then evacuate as previously
outlined.
3.
Weigh in the charge according to the total amount shown
on the unit nameplate.
If weighing facilities are not available or if unit is being
charged during warm weather, follow one of the other
procedures outlined below.
Charge Using Subcooling Method (Fixed Orifice/TXV
Systems) – Outdoor Temperatures 65° F or Above
If charging a fixed orifice or TXV system when the outdoor
ambient temperature is 65° F or above, the subcooling
method can be used to charge the unit.
1.
With the manifold gauge hose on the liquid service port
and the unit operating stably, use a digital thermometer
to record the liquid line temperature.
2.
At the same time, record the liquid line pressure reading.
3.
Use the temperature/pressure chart (Table 5) to
determine the saturation temperature for the liquid line
pressure reading.
Figure 12
Use gauge ports on suction line valve and liquid line valve for evacuation refrigerant lines and indoor
coil. Use suction gauge to measure suction pressure during charging.
Cooling Cycle
