Operation and maintenance manual

Section 260-0130
Operators Compartment - Air Conditioning
SM 1405 Rev 2 11-04
10
gauge (A). The vacuum gauge (A) should remain at this
value when vacuum pressure valve (1) is closed to
indicate that there are no leaks.
8. Open the low side hand valve on the manifold and
vacuum pressure valve (1) and watch that the
gauges start to register that a vacuum is being
drawn. If the gauges do not register the vacuum then
a blockage is present. Open the high side and pump
down until a vacuum of 10 mb is achieved.
9. After 10 - 15 minutes close vacuum pressure valve
(1) and allow the system to settle, vacuum gauge (A)
should not alter. If the vacuum is held, no leaks or
refrigerant contaminated oil is present. If not, open
the vacuum pressure valve (1) and continue
pumping, checking at regular intervals. If there is a
leak, check all fittings and tighten if necessary.
10. Tighten down (turn clockwise) both high and low
side valves on the gauge manifold to the closed
position, remove the service hose (yellow) from the
vacuum connection (6) on vacuum pump and switch
the pump 'Off'.
11. Connect the service hose (yellow) to the R-134a
cylinder. Open the cylinder valve and then purge air
from the hose at the manifold connection.
12. Open the low side hand valve on the manifold
slowly, until low pressure gauge (B) is at bottle
pressure. Watch the high side manifold gauge (C)
rise to ensure that no blockage is present. Close the
manifold valve and cylinder, then disconnect the hose
from the cylinder.
13. Connect the service hose (yellow) to the Nitrogen
cylinder. Open the neck valve on the cylinder and set
the regulator pressure such that it is higher than the
system pressure then purge the hose. Open the low
side hand valve on the manifold, as the pressure
rises open the high side hand valve on the manifold
and allow a system pressure of 10 bar (150 psig) to
be reached. Close all the valves. Using a suitable
electronic leak detector, check all joints in the air
conditioning system for leaks. Tighten any loose
joints and re-test if necessary.
14. Vent the refrigerant mix to atmosphere by
removing the service hose (yellow) from the Nitrogen
cylinder and opening the low side hand valve on the
manifold. Re-evacuate the system to below 6 mb
(steps 7 to 10).
15. Lower hood assembly and remove wheel blocks.
CHARGING THE SYSTEM
Note: Refer to all WARNINGS listed under
'Maintenance' prior to charging the system.
Recommended Equipment Required:
Portable High Vacuum Charging Station
Electronic Leak Detector
or Standard Service Manifold (Refer to Fig. 4)
For New Or Completely Empty System
Note: The charging procedure must be done in
ambient temperatures above 15.5° C (60° F) with the
R-134a canister temperature equal to the outside
ambient temperature.
1. Shut off engine and block all road wheels.
2. Pull on handle to release hood catch and raise the
hood.
3. Remove protective caps from 'quick coupler'
valves on rear of compressor.
4. Connect low pressure gauge hose (blue hose and
gauge) to suction side or low side fitting on
compressor. The suction side can be identified by the
size of the hose connected to the fitting. This will be
the largest diameter hose of the system.
5. Connect the high pressure gauge hose (red hose
and gauge) to discharge or high side fitting on
compressor.
6. Connect yellow supply hose to suction port on
vacuum pump.
7. Open both sides of gauges, low and high, completely.
8. Start vacuum pump to evacuate the complete air
conditioning system.
9. Run vacuum pump for approximately 30 minutes.
Ideal gauge readings should be 29.92 inches of
mercury. The pressure will vary with altitude; it will be
approximately 0.03 bar (0.5 lbf/in²) less for each 305 m
(1 000 ft) of elevation.
10. Before disconnecting power supply from vacuum
pump, close both high and low side gauges. Remove
yellow hose from vacuum pump and connect to
R-134a source.
11. Open R-134a source. Loosen, but do not remove,
yellow supply hose at manifold on gauges to remove all