Refrigerator Defrost thermostat bio metal 3 wire

The refrigerator defrost thermostat with a bi-metal design and 3-wire configuration is a critical component used in automatic defrost systems of modern refrigerators and freezers. This thermostat regulates the defrost cycle by detecting temperature changes and ensuring that the defrost heater turns on only when necessary. Its bi-metal disc responds to temperature variations by mechanically opening or closing the electrical circuit, protecting the evaporator from overheating or freezing.

Applications:

• Domestic refrigerators and freezers

• Commercial refrigeration systems

• Ice makers and display freezers

• HVAC evaporator coils requiring periodic defrost

Features:

• Bi-metal sensing element: Provides reliable temperature switching without electronic components.

• 3-wire configuration: Allows integration with multi-functional defrost and control systems.

• Over-temperature protection: Automatically shuts off heater if excessive heat is detected.

• Durable build: Resistant to moisture, frost, and corrosion.

• Snap-action mechanism: Fast response to temperature change ensures efficient defrost cycles.

• Wide temperature range: Operates effectively in harsh cold environments.

Specifications:

• Type: Bi-metal thermostat (mechanical)

• Wiring: 3-wire configuration (typically includes common, heater, and compressor control)

• Operating Voltage: 120V / 220V AC (model dependent)

• Current Rating: 5A to 10A (varies by design)

• Cut-In Temperature: Approx. -5°C to 0°C

• Cut-Out Temperature: Approx. 15°C to 20°C

• Mounting: Clip-on or screw-mounted on evaporator coil

• Casing: Thermoplastic or metal for insulation and protection

• Certifications: UL, CE (depending on manufacturer)

Questions:

1. How can I test a 3-wire bi-metal defrost thermostat for proper functionality using a multimeter?

2. What are the signs of a faulty defrost thermostat in a refrigerator system?