Traulsen Cabinet Sensor Open or Shorted

What does Traulsen Cabinet Sensor Open or Shorted mean?

This alarm means the controller cannot read a valid signal from the cabinet air sensor because the probe circuit is open or shorted. The cabinet sensor governs cabinet temperature control, so a bad reading leaves the control without reliable feedback. A correct cabinet sensor reads about 32.7K ohms at 32F within ten percent.

Symptoms

• Alarm LED illuminated and horn sounding on the control
• Erratic or implausible cabinet temperature reading
• Cabinet not maintaining temperature properly
• Sensor resistance out of the expected range when tested

Common causes

• Cabinet sensor probe disconnected or loosely connected
• Open circuit in the cabinet sensor wiring
• Shorted cabinet sensor
• Failed cabinet sensor reading outside the 32.7K ohm range at 32F

Diagnostic steps

1. 01

   Locate the cabinet sensor

   Gain access to the cabinet air sensor mounted inside the evaporator housing on the return-air side of the coil.

2. 02

   Check the connection

   Confirm the sensor probe is properly connected; reconnect it if it is loose or disconnected.

3. 03

   Test sensor resistance

   Disconnect the sensor and place the probe tip in an ice-water bath; at 32F resistance should read about 32.7K ohms plus or minus ten percent.

4. 04

   Replace a failed sensor

   If resistance is outside that range, replace the cabinet sensor.

5. 05

   Verify correct placement

   Re-mount the sensor in its correct location on the return-air side so the control reads representative cabinet temperature.

When to call a professional

Call a technician if reconnecting the probe does not clear the alarm or if you are not equipped to meter sensor resistance against the 32.7K-ohm spec. Accessing the sensor inside the evaporator housing, testing the probe in an ice-water bath, and replacing it with correct placement are service tasks; an incorrectly placed or wrong-value sensor will keep the control from regulating temperature.