Thermistor
Common temperature-sensing fault part. Confirm resistance range and connector.
Traulsen RLT Series Error Codes — What They Mean
The Traulsen RLT Series are reach-in commercial refrigerators designed for demanding foodservice environments. Traulsen (a Welbilt brand) is known for its premium construction and is commonly found in high-volume kitchens, healthcare facilities, and high-end hotel operations. RLT series units use Traulsen’s Compu-Med or Digital Control System (DCS) controller, which provides error code readouts and temperature logging. The DCS controller is standard on newer RLT models and offers USB data export for HACCP compliance.
Traulsen RLT Digital Control System Error Code Reference
| Code | Fault |
|---|---|
| E1 | Box temperature sensor fault |
| E2 | Evaporator inlet temperature sensor fault |
| E3 | Evaporator outlet temperature sensor fault |
| E4 | Defrost termination sensor fault |
| E5 | High temperature alarm |
| E6 | Low temperature alarm |
| E7 | Defrost timeout |
| E8 | Door open alarm |
| E9 | Probe 1 or Probe 2 open-circuit |
| Er | System error — communication between controller and relay board |
Common Causes by Code
- E1 — Box temperature sensor — The box sensor on Traulsen units is mounted in the upper interior. In heavy-use kitchens, steam and moisture from food operations can corrode the sensor connector within 2–3 years. Check the connector first before ordering a new sensor.
- E5 — High temperature — Traulsen RLT condensers are bottom-mounted and front-accessed. In high-use kitchen environments, the condenser can be completely blocked within weeks. A monthly condenser cleaning schedule is appropriate for high-volume kitchens.
- E7 — Defrost timeout — Traulsen RLT units use electric defrost heaters wrapped around the evaporator coil. If the heater is energized but ice isn’t melting, the heater may be failing (reduced wattage due to a partially open element) or the defrost termination thermostat has failed in the open position.
- Er — System error — The controller’s relay board (which controls heater, fan, and defrost circuits) is not communicating with the main controller. This occurs after a power surge or when moisture has reached the relay board connector.
- E9 — Probe open-circuit — The probe is completely disconnected or the thermistor element has failed open. This is distinct from E1 (sensor fault, which may be an out-of-range reading) — E9 means zero signal from the probe.
Step-by-Step Fix
- Check the DCS display — The Traulsen DCS controller displays the error code and a short text description. To view historical fault data, navigate to the DCS menu under Data Log. Some RLT models can export this log to USB.
- For E5 (high temperature) — Clean the condenser before any other investigation. Traulsen RLT condensers are accessible from the front kick plate. Use a condenser brush or low-pressure compressed air — vacuum first, then use coil cleaner spray if needed.
- For E7 (defrost timeout) — Access the evaporator compartment by removing the interior back panel. Measure defrost heater resistance with an ohmmeter (power off). A heater with normal resistance but not heating indicates a failed relay on the DCS relay board.
- For E1 or E9 (sensor) — Disconnect the sensor from the controller board. Use a temperature-verified source (a cup of ice water at 32°F or a reference thermometer) and measure the sensor resistance — compare to the expected resistance at that temperature using the Traulsen NTC curve.
- For Er (system error) — Power cycle the unit (unplug for 60 seconds). If Er returns, inspect the cable between the controller display and the relay board — it is often a ribbon cable or multi-pin connector that can loosen over time.
Parts Often Needed
| Part | Notes |
|---|---|
| Box temperature sensor | Traulsen specific; verify probe length and connector |
| Defrost heater | Match wattage; multiple heaters on some RLT models |
| Defrost termination thermostat | Check cutout temperature |
| DCS relay board | For Er fault; verify cable before replacing board |
| Door gasket | Traulsen magnetic gasket; order by door and hinge orientation |
| Evaporator fan motor | Match existing specifications |
Need Replacement Parts?
Before ordering, match the refrigeration part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
Traulsen is a premium commercial refrigeration brand — warranty service must be performed by Welbilt/Traulsen authorized service agents to maintain the warranty. HACCP data logging through the DCS system is a critical food safety feature for healthcare and institutional kitchens — any fault that compromises temperature logging should be addressed immediately by a qualified refrigeration technician.