Introduction to Walk-In Freezers : Failure Types

 1. Defrost System Malfunction:

• Excessive Ice Buildup: Compressor runs continuously, and desired temperature isn't maintained.
• Water Drainage Issues: Structural damage if water from evaporator ice doesn't drain properly.
• Checkpoints: Defrost time clock, defrost thermostat, defrost control, and defrost heater.

2. Condenser Issues:

• Lack of Airflow: Causes excessive pressures and temperatures due to restricted airflow or failing fan motor.
• Dirt Build-Up: Restricts airflow in condenser coils, increasing pressure and power consumption.
• High-Pressure Switch: May trip due to overheating caused by poor airflow.

3. Compressor Failures:

• Common Causes: Overheating, flooded starts, floodback, and lack of lubrication.
• Refrigerant Migration: Ensure pump down solenoids, low-pressure controls, and crankcase heaters are functioning.
• Faulty Motor or Pumping Mechanism: Usually due to external conditions that need correction.

4. Refrigerant Issues:

• Leaks: Caused by poor mechanical joints (brazed or flared fittings). Inspect for oil residue to identify leaks.
• Overcharge: Increased pressure, lower than normal superheat, potential liquid floodback to the compressor.
• Undercharge: Insufficient refrigerant, resulting in frozen evaporator coils, excessive superheat, lower suction, and discharge pressures. Compressor may cycle at its overload protector.

5. Drain Pan Problems:

• Improper Installation or Heat Tape Failure: Leads to water or ice on the floor.

6. Door Issues:

• Improper Closure or Bad Gaskets: Allows warm air to enter, raising box temperature and causing system failures.
• Faulty Heater Strips: Prevent moisture from freezing around the door. Measure amperage draw to ensure operation.

7. Solenoid Valve Issues:

• Stuck Open/Closed: Causes valve leaks or non-functionality due to an open circuit in the electrical coil.

8. Temperature Sensor and Thermostat Failures:

• Faulty Sensors: Circuit board feedback shows inconsistent temperatures.

9. Improper System Sizing:

• Incorrect Sizing: The unit fails to maintain temperature if the size or product load doesn't meet factory recommendations.
• Continuous Compressor Operation: Caused by improper sizing or incorrect product load.

Preventive Measures:

• Regular maintenance checks.
• Cleaning coils and ensuring proper airflow.
• Monitoring temperature and humidity levels.
• Verifying door seals and gaskets.
• Ensuring correct refrigerant charge.