Carrier Container Refrigeration Unit 69NT40-511-3

Ensure a pressure regulator is attached to the nitrogen cylinder

Ensure no oxygen is present near the refrigeration system

Remove the high pressure switch as outlined in section 6.12.1

Connect ohmmeter or continuity light across switch terminals

Connect hose to a cylinder of dry nitrogen

Prepare an ice-water bath at 0°C (32°F)

Ensure the ohmmeter is calibrated and ready for use

Sensor Placement and Initial Check

Place the sensor in the ice-water bath

Check air temperature/data readout on the control panel

Is the air temperature/data readout 0°C (32°F)?

Ensure no mixing of refrigerants with air for leak testing.

Use R-134a electronic leak detector for finding leaks.

Test joints with soapsuds for large leaks.

System Charging and Leak Checking

Charge the system with refrigerant to build up pressure between 2.1 to 3.5 kg/cm² (30 to 50 psig).

Remove refrigerant cylinder and leak-check all connections.

Ensure only the correct refrigerant cylinder is used to pressurize the system.

Checking the Refrigerant Charge

Set the controller set point to -25°C (-13°F)

Ensure the suction modulation valve is fully open

Connect the gauge manifold to the compressor service valves

Enter the compressor discharge pressure

Is the refrigerant level within the sight glass boundaries?

Adding Refrigerant to System (Full Charge)

Evacuate unit and leave in deep vacuum

Open door and remove chart nut and platen.

Push voltage indicator test switch. Is the voltage indicator in the red or white zone?

Replace battery if voltage indicator points to the red or white zone.

Place recorder bulb in ice bath for 10 minutes.

Rotate the chart by hand and check the stylus indicated temperature.