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4
12
10
13
6
7
8
17
UPS2
UPS1
18
19
1. Compressor
2. Discharge Line
3. Discharge Line
Check valve
4. Condenser Coil
5. Receiver
6. Drier Inlet Valve
7. Drier
8. Drier Outlet Valve
9. Thermal Expansion
Valve
10. Evaporator Coil
11. Suction Line
12. Subcooler
13. Liquid-Suction Heat
Exchanger
Figure 4-4. Evacuation Set-Up
T-288
9
5
14
UPS3
2
11
CFS
15
16
1
20
21
22
23
14. Charge Isolation
Valve
15. Discharge Service
Valve
16.
Suction Service
Valve
17. Liquid Line Solenoid
Valve
18. Refrigerant
Reclaimer
19. Vacuum Manifold
20. Thermistor Vacuum
Gauge
21. Compound Gauge
22. Vacuum Pump
23. Refrigerant Cylinder
4.8
ADDING REFRIGERANT TO SYSTEM
a.
Installing a Full Charge
1. Install a manifold gauge set as outlined in
section 4.3.
2. Evacuate and dehydrate the system as
outlined in section 4.7.b, as applicable, if not
completed at this time.
3. Place the R-134a refrigerant cylinder on the
scale and connect charging line from the
cylinder to the filter-drier inlet valve. Purge
charging line at valve.
4. Note weight of refrigerant cylinder.
5. Open liquid valve on refrigerant cylinder. Open
filter-drier inlet valve half way and allow the
3
liquid refrigerant to flow into the unit. Monitor
weight of refrigerant cylinder to determine how
much refrigerant is entering the system. The
correct charge is 17 lbs.
6. When refrigerant cylinder weight (scale)
indicates that the correct charge has been
added, close liquid line valve at the cylinder
and backseat the filter-drier inlet valve.
Disconnect lines. Check refrigerant charge.
(See section 4.9.)
If the entire charge cannot be added, a partial
charge may be necessary.
b.
Adding a Partial Charge
1. Start the vehicle engine and allow unit to
stabilize.
2. Place the R-134a refrigerant cylinder on the
scale and connect charging hose from
refrigerant cylinder vapor valve to the
compressor suction service valve. Purge
charging line.
3. Open the refrigerant cylinder vapor valve.
Midseat suction valve (if used) and monitor the
weight of the cylinder to add the remaining
refrigerant. When the correct charge level is
obtained, as outlined in section 4.9, turn off
cylinder
charging
compressor suction service valve.
4. Disconnect manifold gauge set.
4.9
CHECKING THE REFRIGERANT CHARGE
The following conditions must be met to
accurately check the refrigerant charge:
a. Bus engine operating at high idle.
4-6
valve
and
backseat
NOTES
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