Door latch switch
Common interlock fault part on appliance no-start errors.
True T-49 Error Codes — What It Means
The True T-49 is a two-door commercial reach-in refrigerator commonly used in restaurants, prep kitchens, and stores. Depending on build year, it uses a Dixell, LAE, or True-branded digital temperature controller. Most T-49 error codes relate to temperature probes, defrost timing, or high cabinet temperature.
Common Causes
- Temperature probe fault — The cabinet or evaporator sensor is open or shorted.
- High temperature alarm — Dirty condenser coil, bad condenser fan, or door left open.
- Defrost fault — Evaporator iced over due to failed heater, timer, or defrost sensor.
- Airflow restriction — Product blocking evaporator discharge or return path.
Step-by-Step Fix
- Identify the controller model and read the exact alarm code on the display.
- Clean the condenser coil thoroughly. True units are very sensitive to dirty coils.
- Check the condenser fan motor and evaporator fan motors for operation.
- Inspect the door gaskets and confirm doors close fully.
- If the alarm is a probe code, unplug the sensor and measure resistance against the service chart.
- If the evaporator is iced solid, manually defrost the cabinet and inspect the defrost system.
Parts Often Needed
| Part | Notes |
|---|---|
| Cabinet probe | Match controller type and sensor curve |
| Evaporator probe | Often clipped to the suction line or coil |
| Condenser fan motor | Common T-49 service part |
| Door gasket | Replace if torn or not sealing |
Technician Tips
When diagnosing commercial refrigeration faults, start with the controller’s alarm history. Most digital controllers (Dixell, Carel, Eliwell) store the last 5-10 alarms with timestamps. An E1 alarm that appears consistently every few hours suggests a sensor going bad — the resistance value drifts until it’s out of range. An intermittent HI/LO alarm that appears only during hot afternoons suggests a condenser issue, not a sensor fault.
Prevention: Schedule quarterly condenser coil cleaning. Dirty coils are the #1 cause of high-head-pressure faults and compressor overheating in commercial refrigeration. Use a soft brush and compressed air — never a pressure washer on the coil fins.
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
If the compressor is short-cycling, the evaporator is icing repeatedly, or you suspect a refrigerant problem, bring in a commercial refrigeration technician. Sensor faults are simple. Sealed-system issues are not.