Carrier Container Refrigeration Unit 69NT40-511-9

Ensure power to the unit is OFF and power plug disconnected

Disconnect the suction modulation valve coil wires by unplugging the connector

Test each lead’s resistance to ground using a digital ohmmeter

Is there a ground short present?

Inspect the length of wiring for damaged or exposed wires and replace if necessary

Check coil’s resistance using a digital ohmmeter set to low range

Is the coil’s resistance below five ohms?

Plug in the connector for the modulation valve

Turn unit OFF and disconnect power supply

Refer to section 6.27 for removal of the Controller module

Sensor Identification and Measurement

Select the sensor type to be checked

Measure the ohms resistance using the plug connector marked 'EC'

Refer to Table 6-1 for resistance readings

Fill a thermos container with ice cubes or chips

Fill voids between the ice with plain water

Stir the solution until the mixture registers 0 to 0.3°C (32 to 32.5°F) using a laboratory thermometer

Resistance Thermometer Calibration

Immerse the resistance thermometer in the 0°C (32°F) solution

Is the recommended length of the check probe immersed?

Does the resistance thermometer accurately reflect 0°C (32°F)?

Turn unit power OFF and disconnect power supply.

Remove and save any cover over wiring and probe holder, if present.

Cut cable 5 cm (2 inches) from shoulder of defective sensor and discard the defective probe only.

Save cap and grommet assembly for reuse on the replacement probe.

Cut one wire of existing cable 41 mm (1-5/8 inches) shorter than the other wire.

Cut one replacement sensor wire (opposite color) back 41 mm (1-5/8 inches).

Operate the unit in cooling mode for at least 20 minutes

Check the front oil sight glass for foaming after 20 minutes of operation

Is the oil foaming excessively?

Check the refrigerant system for flood-back of liquid refrigerant if oil is foaming excessively

Turn unit off to check the oil level

Check if the oil level is between the bottom to one-eighth level of the sight glass

Remove oil from the compressor if the level is above one-eighth

Add oil to the compressor if the level is below the bottom of the sight glass

Adding Oil with Compressor in System