Randell E03

What does Randell E03 mean?

On a Randell prep table with the Danfoss controller, E03 is the S3 Sensor Failure alarm. S3 is one of the controller's temperature sensors (thermistors). E03 indicates the controller cannot read a valid value from S3 because the sensor has failed, gone out of range, or lost its connection, affecting the function that sensor monitors.

Symptoms

• Display shows E03 with the alarm LED lit
• Temperature control tied to the S3 sensor is affected
• Displayed temperature may be missing or incorrect
• Cooling or defrost behavior may be abnormal

Common causes

• Failed or out-of-range S3 thermistor
• Disconnected or loose S3 sensor connector at the controller
• Damaged sensor wiring
• Controller input fault

Diagnostic steps

1. 01

   Confirm the alarm

   Verify the Danfoss display reads E03, the S3 Sensor Failure alarm.

2. 02

   Disconnect power before inspecting

   Ensure the unit is disconnected from its power source before checking the sensor or wiring, per the manual.

3. 03

   Inspect the S3 sensor connection

   Check that the S3 thermistor is connected at the controller and that its wiring is not damaged or loose.

4. 04

   Verify cabinet temperature

   Compare the displayed temperature against the set point to judge whether the unit is still holding safe temperature.

5. 05

   Contact service

   The Danfoss table directs contacting service for a sensor failure; call 888-994-7636 to test or replace the S3 thermistor.

When to call a professional

The Danfoss code table directs contacting service for an S3 sensor failure. Pinpointing the faulty thermistor and replacing it with the correct OEM part should be handled by a Randell Authorized Service Agent, since the manual requires factory-authorized service with OEM parts on these R290 units. Call service at 888-994-7636 if E03 does not clear after checking the connection.