E-stat Controller

E-stat Controller

The E-stat controller is used to prevent the evaporator core from freezing.

The NTC probe senses the temperature of the air as it passes through the evaporator core. An electronic control circuit interprets the change in resistance of the thermistor to indicate when the evaporator core is near freezing. The control circuit then provides an output to disengage the compressor clutch, allowing the evaporator core to warm. When the air temperature of the evaporator core warms up, the circuit reactivates the clutch allowing the evaporator to cool.



  • High sensitivity
  • High reliability
  • Wide application voltage
  • Customizable range of drive current outputs and unlimited packaging designs


Temperature controller for automobile air conditioners


Off 3.5 ±0.3°F (0.5°C)
On 3.0°F (5.0°C) reference
Differential 1.5 ±0.3°F (0.5°C)
Voltage Drop Maximum 0.3 V
Response Time 4 seconds; moves from air at 68°F (20°C) to liquid at 23°F (-5°C)




Schematic Diagram



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