Traulsen Defrost Termination by Time

What does Traulsen Defrost Termination by Time mean?

This alarm reports that defrost cycles have ended on the time limit instead of reaching the defrost termination temperature for 72 hours. Normally defrost should clear the coil and terminate on temperature; consistently timing out suggests the coil is not reaching termination temperature, often because of a defrost heater problem, an iced coil, or a coil sensor issue.

Symptoms

• Alarm LED illuminated and horn sounding on the control
• Defrost cycles repeatedly ending on the time limit
• Evaporator coil remaining iced after defrost
• Cabinet temperature drifting up over time

Common causes

• Failed or weak defrost heater not reaching termination temperature
• Evaporator coil iced up or airflow restricted
• Coil sensor failed or out of position
• Incorrect defrost parameters in the controller

Diagnostic steps

1. 01

   Inspect the evaporator coil

   Check whether the coil is iced up and confirm there is proper airflow through it; clear restrictions or duct issues.

2. 02

   Check the defrost heater

   Verify the defrost heater is operating so the coil can reach termination temperature.

3. 03

   Test the coil sensor

   Check the coil sensor connection and resistance against the 32.7K-ohm-at-32F spec; replace the sensor if it is failed.

4. 04

   Confirm correct sensor placement

   Ensure the coil sensor is in the correct position for the model so it reads true coil temperature.

5. 05

   Review defrost parameters

   Check the defrost (DEF) settings in the controller parameters and reset them if they are not OK.

When to call a professional

Call a technician if defrost keeps timing out after checking for an iced coil and airflow. Diagnosing a failed defrost heater, replacing the coil sensor, and adjusting controller defrost parameters require electrical service skills and access to the manual's parameter and removal procedures. Letting the coil stay iced will keep raising cabinet temperature and stress the system.