Thermistor
Common temperature-sensing fault part. Confirm resistance range and connector.
Commercial Refrigeration Error Codes — Complete Reference
Commercial refrigeration equipment across all major brands shares common alarm patterns. This guide covers the universal error codes and what they mean for walk-in coolers, reach-in refrigerators, freezers, and commercial ice machines.
Universal Alarm Patterns
High Temperature Alarms (E2, Code 1, HI, Alarm 1)
Every commercial refrigeration controller has a high temperature alarm. If your unit shows E2, HI, Code 1, or similar: the cabinet temperature exceeded the alarm setpoint. Immediate action required — product at risk.
Check first: Door seals, condenser cleanliness, fan motors running.
Temperature Sensor Faults (E1, Code 7, Sensor Fault)
The NTC thermistor used to monitor cabinet temperature has failed or is reading out of range. Test resistance: 10kΩ NTC reads ~10kΩ at 77°F. Open circuit = replace.
Defrost Faults (E3, Code 5, Defrost Alarm)
The defrost cycle failed to complete or terminate correctly. Check defrost heater (test resistance), defrost termination thermostat (should be closed at room temp), and drain for ice blockage.
Fan Motor Faults (E4, Code 6, Fan Alarm)
Evaporator or condenser fan motor failure. Check motor for seizure, run capacitor, and correct rotation direction.
Pressure Faults (E5, Code 3/4, High/Low Pressure)
Refrigerant circuit fault. High pressure = dirty condenser or overcharge. Low pressure = low refrigerant or TXV fault. Requires EPA 608-certified technician.
Brand-Specific Code Guides
| Brand | Code Guide |
|---|---|
| Hoshizaki | E1-E9 (ice machines), F1-F3 |
| Manitowoc | Codes 1-10, E01-E06 (Indigo) |
| True | E1-E4, HI |
| Beverage-Air | E1-E3 |
| Turbo Air | E1-E2 |
| Continental | E1 |
| Traulsen | E1-E2 |
| Master-Bilt | Codes 1-5 |
| Delfield | E1 |
| Nor-Lake | E1 |
| Heatcraft/Bohn/Larkin | Alarms 1-7 |
| Hussmann | E1-E5 |
Parts That Fix 80% of All Commercial Refrigeration Alarms
| Part | Which Alarms It Fixes |
|---|---|
| NTC temperature sensor | E1, Sensor Fault, Code 7 |
| Defrost heater | E3, Code 5, Defrost Fault |
| Defrost termination thermostat | E3, Code 5 |
| Evaporator fan motor | E4, Code 6, Fan Alarm |
| Door gasket | E2, HI, High Temp |
| Condenser fan motor | E2, High Temp (when condenser-related) |
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.
Related Resources
- Browse all commercial refrigeration error codes — True, Hoshizaki, Manitowoc, and more
- Alto-Shaam Commercial Oven Error Codes — Guide
- Beverage-Air Refrigerator Error Code E1 — Causes & Fix
- Beverage-Air Refrigerator Error Code E2 — Evaporator Sensor …
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
Any pressure fault (high or low) indicates a refrigerant system issue requiring EPA 608 certification. Do not attempt to add refrigerant without finding and repairing the leak.