Carrier 69NT40-561-300, Operation And Service Manual

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T-365 7–12
26.Backseat all service valves, and run in full cool.
27.Verify refrigerant charge level per the unit s operation/service manual.
28.Perform a leak check of the system.
29.Replace any removed wire tie wraps and reinstall compressor guard.
30.If failure occurs under the unit’s warranty, tag the replacement part for cause of failure and collect an all data
download for failure analysis.
7.9 HIGH PRESSURE SWITCH
7.9.1 Checking High Pressure Switch
WARNING
!
Do not use a nitrogen cylinder without a pressure regulator.
NOTICE
The high pressure switch is non-adjustable.
1. Remove switch as outlined in Figure 7.9.2 .
2. Connect ohmmeter or continuity light across switch terminals. Ohm meter will indicate no resistance or con-
tinuity light will be illuminated if the switch closed after relieving compressor pressure.
3. Connect hose to a cylinder of dry nitrogen. (See Figure 7.11 )
Figure 7.11 High Pressure Switch Testing
4. Set nitrogen pressure regulator at 26.4 kg/cm
2
(375 psig) with bleed-off valve closed.
5. Close valve on cylinder and open bleed-off valve.
6. Open cylinder valve. Slowly close bleed-off valve to increase pressure on switch. The switch should open at
a static pressure up to 25 kg/cm2 (350 psig). If a light is used, the light will go out. If an ohmmeter is used,
the meter will indicate open circuit.
7. Slowly open bleed-off valve to decrease the pressure. The switch should close at 18 kg/cm
2
(250 psig).
7.9.2 Replacing High Pressure Switch
1. Remove the refrigerant charge.
2. Disconnect wiring from defective switch. The high pressure switch is located on the discharge connection or
line and is removed by turning counterclockwise.
3. Install a new high pressure switch after verifying switch settings.
4. Evacuate, dehydrate and recharge the system.
5. Start the unit, verify refrigeration charge and oil level.
Cylinder Valve & Gauge
Pressure Regulator
Nitrogen Cylinder
Pressure Gauge
Bleed-Off Valve
1/4 Inch Connection