Johnson Controls A421 Series Electronic Temperature Control – Product Spotlight

Johnson Controls’ A421 Series Electronic Temperature Controls are single stage controls with a single-pole, double-throw output relay.



The A421 features a bright backlit LED with adjustable brightness and a three button touchpad interface that can be set up to restrict user adjustments. An LED in the middle of the unit indicates the On/Off status of the relay. Standard A421 series control modules have simple on and off temperature settings for heating or cooling, an adjustable anti-short cycle delay, temperature setback, and sensor offset capability. The temperature control range is -40 to 212 degrees F.

A421 series controls are available in multiple enclosure offerings, including Type 1/IP20, high-impact plastic enclosures suitable for surface or DIN rail mounting, or in Type 4X/IP67 watertight, corrosion-resistant surface mount enclosures.

Adjustable on and off temperature setpoints assist with quick setup, choosing either cooling or heating control applications using the three-button touchpad. This eliminates the need to remove the cover and reposition the jumpers for reverse or direct control actions.

High and low temperature setpoint adjustment stops allow end users to set up applications for the desired range of adjustment, and restrict user adjustment to just the desired temperature adjustment range.

Additional features include displayed temperature offset, adjustable anti-short cycle delay, temperature setback and offset control, and low and line-voltage control models.

For more information about Johnson Controls’ A421 Series Electronic Temperature Controls, contact our experts today!


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