Temperature sensor
Common error-code part. Confirm resistance and connector style.
True Refrigeration E6 Error Code — What It Means
True Refrigeration error code E6 is commonly a high box temperature alarm. The controller has measured cabinet temperature above the allowed limit for too long, which means the unit is losing capacity, airflow, or temperature control. In a restaurant or convenience store, E6 usually shows up after a dirty condenser, weak evaporator airflow, a door left open, or a refrigeration system problem that prevents the cabinet from pulling down.
Common Causes
- Dirty condenser coil — A grease-loaded condenser is the most common cause. Head pressure rises and cooling capacity drops.
- Evaporator fan not moving air — If the cabinet air cannot circulate across product, the controller sees warm box temperature even though part of the coil is cold.
- Door gasket leak or door left open — Warm kitchen air floods the cabinet and keeps product temperature high.
- Low refrigerant or sealed system restriction — The compressor runs but the unit never reaches setpoint.
- Faulty temperature probe — A drifting cabinet sensor can report a false high-temperature condition.
Step-by-Step Fix
- Verify actual cabinet temperature — Use a calibrated thermometer in product simulant or between products. Do not rely only on the display.
- Clean the condenser coil — Brush and vacuum the coil, then use coil cleaner if grease is heavy. Most E6 calls start here.
- Check condenser and evaporator fan operation — Confirm all fan motors spin at full speed and move air in the correct direction.
- Inspect door gaskets and door closure — Look for torn gaskets, sagging doors, and product blocking the door from sealing.
- Compare displayed temperature to a known thermometer — A large mismatch points to a sensor issue rather than a true temperature problem.
- Look for frost pattern problems — If the evaporator is only partially frosted or the suction line is abnormal, suspect refrigerant charge or a restriction.
- Reset the alarm and monitor pull-down — After cleaning and repairs, confirm the cabinet returns to setpoint and holds it.
Parts Often Needed
| Part | Notes |
|---|---|
| Condenser fan motor | Replace if the motor is slow, noisy, or stalled |
| Evaporator fan motor | Loss of box airflow drives warm product temps fast |
| Door gasket | Match the cabinet series and door size |
| Temperature probe | Replace if display temperature does not match actual box temp |
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 machine-control 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
Call a refrigeration tech if the cabinet still will not pull down after coil cleaning, fan checks, and gasket inspection. Warm box alarms that come back with a clean coil often point to low charge, a restricted metering device, or a weak compressor.
See Also
- True Refrigeration Error Codes — Complete Guide
- True Refrigeration E3 Error Code — Causes & Fix
- True Refrigeration E4 Error Code — Causes & Fix
- True Refrigeration T-Series Error Codes — Complete Guide