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5-6
i. Install a new filter-drier. Evacuate the unit to 500 microns. Close off the vacuum pump valve and stop the
pump. Wait five minutes to see if the vacuum holds. This checks for residual moisture and/or leaks.
j. With a vacuum still in the unit, the refrigerant charge may be drawn into the system from a refrigerant con-
tainer on a scale. See
for correct charge. Continue to
. for procedure to install a
complete charge.
5.6
CHARGING THE REFRIGERATION SYSTEM
Figure 5.3 Procedure for Adding a Complete Charge
1. Suction Valve (Low Side)
2. Manifold Gauge Set
3. Discharge Valve (High Side)
4. Dead Head Port
5. Refrigerant Cylinder
6. King Valve Access Port
7. King Valve
8. Liquid Line Charging Port
- - - - -
5.6.1
Checking The Refrigerant Charge
a. Start unit in cooling mode and run approximately ten minutes.
b. Partially block off air flow to condenser coil so discharge pressure rises to 325 psig (22 Bar).
c. The unit is correctly charged when there are no bubbles in the sight glass.
5.6.2
Installing A Complete Charge
NOTE
The ambient (air entering the condenser) air temperature should be above 40°F (4.4°C)
a. Evacuate the refrigeration circuit leave in a deep vacuum. Refer to
for more information.
b. Place refrigerant R-134a cylinder on a scale. Connect the discharge gauge field coupler of the manifold test set
to the king valve or liquid line charging port. Connect the suction pressure hose of the manifold gauge set to the
manifold dead head port. Connect a charging line between the center tap of the second gauge set and the
refrigerant drum. Mid-seat the discharge knob. Open the liquid valve on the drum and purge all hoses. Front-
seat the discharge knob. (Refer to
)
c. Note the weight of the refrigerant cylinder.
d. Open the liquid valve on the refrigerant cylinder. Open the king valve or field coupling attached to the liquid
line charging port half way and allow the liquid refrigerant to flow into the unit until the correct weight of
refrigerant has been added as indicated by scale. See
for correct charge.
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