Pretrip Test

A Pretrip Test verifies unit operation. The PRETRIP Key allows either a Full Pretrip Test or an Engine Running Pretrip Test to be initiated by the operator.

Parent topic: Truck Standard Display HMI Control Panel

Pretrip Test Conditions

  • The current unit settings are saved and restored at the end of the Pretrip Test or if the unit is turned off and back on.

  • The Pretrip Test can be run in either Diesel or Electric Mode.

  • The unit will auto switch from Diesel Mode to Electric Mode or from Electric Mode to Diesel Mode during a Pretrip Test if these features are enabled and the auto switch conditions occur.

Conditions Where Pretrip Tests are not Allowed

  • Pretrip Tests are not allowed if any Shutdown Alarms are present.

  • Pretrip tests are allowed with some Check and Log Alarms present.

Pretrip Test Sequence

Pretrip tests proceed in the order shown below. A Full Pretrip Test is started with the engine or motor not running and includes all tests. A Running Pretrip Test is started with the engine or motor running and does not include the Amp Checks or Engine Start Check.

  • Amp Checks - Each electrical control component is energized and the current drawn is confirmed as within specification.

  • Engine Start - The engine will start automatically.

  • Defrost - If the coil temperature in a zone is below 45°F (7°C), a defrost cycle is initiated for that zone.

  • RPM Check - The engine RPM in high and low speed is checked.

  • Zone 1, 2, or 3 Cool Check - The ability of the zone to cool in low speed is checked.

  • Zone 1, 2, or 3 Heat Check - The ability of the zone to heat in low speed is checked.

  • Zone 1, 2, or 3 Return to Cool Check - The ability of the zone to return to cool mode is checked.

  • Report Test Results - The test results are reported as PASS, CHECK, or FAIL when the Pretrip Test is completed. If test results are CHECK or FAIL, alarm codes will exist to direct the technician to the source of the problem.

Pretrip Test Considerations

Important Always perform Pretrip with the dividing wall(s) in place. Running a Pretrip with the dividing wall(s) removed may result in false test results.

When performing a Pretrip Test, the following issues should be considered.

  • Whenever possible, run the Pretrip Test with an empty truck box.

  • If running a Pretrip Test on a truck loaded with dry cargo, verify that proper airflow can occur around the load. If the load restricts airflow, false test results may occur. Units have high refrigeration capacity which results in rapid temperature change. Sensitive dry cargo may be damaged as a result.

  • If running a Pretrip Test on a truck that has just been washed down, the extremely high humidity inside the truck box may result in false test results.

  • If running a Pretrip Test on a truck loaded with sensitive cargo, monitor the load temperature during the test as normal temperature control is suspended during pre-trip operation.

  • Always perform Pretrip Tests with the cargo doors closed to prevent false test results.