Refrigeration Maintenance and Service Operations
135
possible and as large in diameter as possible. For
example, it takes eight times as long to pull a
given vacuum through a 6 mm (1/4 inch) diameter
hose as it does through a 12 mm (1/2 inch)
diameter hose. It takes twice as long to pull a
vacuum through a 2 meter (6 foot) long hose as it
does through a 1 meter (3 foot) long hose.
Heat Saves Time
A useful and practical time saver is the application
of heat to the system. Increasing the temperature
of the compressor oil and refrigerant will speed up
the vaporization of any water present in the
system.
Heat lamps, electric heaters, or fans can be
applied to the compressor crankcase and other
parts of the system to increase the temperature of
the refrigerant and compressor oil.
Unit Charging (from an Evacuated
Condition)
1. Close valve V4.
2. Open the Gas Ballast valve (located on top of
the pump housing behind the handle).
3. Stop the vacuum pump.
4. The discharge valve remains mid-seated.
5. Connect the refrigerant tank with gauge
manifold to the evacuation station (see
“Evacuation Station and Unit Hookup” in this
chapter).
6. Weigh the tank of refrigerant.
7. Check the unit data plate for the required
weight of refrigerant charge then subtract the
amount of the charge to be input to your unit
from the total weight of the tank of refrigerant.
This provides final tank weight after the unit
receives a full system refrigerant charge.
8. Set the refrigerant tank for liquid removal.
Open the hand valve on the tank.
9. With the unit OFF, open the gauge manifold
hand valve and charge liquid refrigerant into
the system.
10. Close the refrigerant tank hand valve when the
correct amount (by weight) of refrigerant has
been added or if the system will take no more
liquid.
The unit is now ready to have the Evacuation
Station removed (described in the following steps,
“Evacuation Station Removal”). See following,
“Final Charging Procedure for Partially Charged
Units” to complete charging procedure.
Evacuation Station Removal
1. Back seat the discharge service valve.
2. Remove the service hose from the refrigerant
tank service fitting. Cap the receiver tank
service port.
3. Operate the unit in cool mode.
4. Open the hand valve at the gauge manifold
and read suction pressure.
WARNING: Never use a torch or other
concentrated heat source to heat the
compressor or other refrigeration system
component.
1.
Close the vacuum valve and watch the
movement of vacuum gauge needle. If needle
shows a pressure rise but finally levels off to a
constant pressure, the system still contains to
much moisture. Dehydration and additional
evacuation time are required.
2.
Time
3.
Pressure (Vacuum)
4.
Atmospheric Pressure
Figure 46: Pressure Rise Levels Off after
Evacuation Indicates Moisture in System
Summary of Contents for CRR-40 119
Page 4: ......
Page 16: ...Safety Precautions 16...
Page 18: ...Service Guide 18...
Page 20: ...Model Features 20...
Page 32: ...Specifications 32...
Page 120: ...MP 3000a Controller 120...
Page 160: ...Wiring and Schematic Diagrams Index 160...
Page 161: ...161 MPC2000 Wiring Schematic...
Page 162: ...162 MPC2000 High Voltage Wiring Diagram...
Page 163: ...163 MPC2000 Low Voltage Wiring Diagram...
Page 164: ...164 MPC2000 WCC Wiring Schematic...