A421GEF-01C | Single Stage Temp Controller with Sensor, 24VAC, NEMA4X, 9
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Brand: Johnson ControlsSKU: A421GEF-01C

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A421GEF-01C | Single Stage Temp Controller with Sensor, 24VAC, NEMA4X, 9" lead, -40 to 212F, HTG/CLG | Johnson Controls

Johnson Controls | A421GEF-01C
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Details for A421GEF-01C


Single Stage Temp Controller with Sensor, 24VAC, NEMA4X, 9" lead, -40 to 212F, HTG/CLG


The A421 Series controls are single stage, electronic temperature controls with a single-pole, double-throw (SPDT) output relay. The controls feature an adjustable backlit LCD for viewing the temperature and status of other functions, and a three-button touchpad for setup and adjustment. An LED indicates the On/Off status of the output relay.

The A421 controls are available in low voltage 24 VAC and high voltage 120 or 240 VAC models, which provide options for most refrigeration and HVAC applications.

The A421 controls provide heating or cooling control, sensor offset, temperature setback, adjustable anti-short cycle delay, and a restricted user adjustment mode. The temperature units can be displayed in °F or °C.

The temperature adjustment range is -40 to 212°F or -40 to 100°C. The A421 controls are available in Type 1, IP20 high-impact plastic enclosures suitable for surface or DIN rail mounting and Type 4X, IP66 watertight, corrosion-resistant surface mount enclosures.

Refer to the A421 Series Electronic Temperature Controls Product Bulletin (LIT-12011972) for important product application information.


The A421 Electronic Temperature Control can be used to control a wide variety of single-stage refrigeration or HVAC equipment.

Sample temperature control applications include:

  • temperature monitoring and alarming
  • on/off control of boilers and chillers
  • boiler and chiller pump control
  • heating and cooling control
  • cooling tower fan control based on water temperature
  • supply, makeup, and mixed air temperature control
  • temperature actuated valve control
  • supply and makeup air damper and fan control
  • condenser fan control based on condenser temperature.


Item Number A421GEF-01C
Brand Johnson Controls
Housing NEMA4X
Type Temperature Controller
Voltage 24VAC

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