A421AEJ-02C Johnson Controls Temperature Control

Overview

The Johnson Controls A421AEJ-02C is a single-stage electronic temperature control designed for efficient temperature management in HVAC and refrigeration applications. It features a high-impact, thermoplastic Type 4X (NEMA) watertight and corrosion-resistant enclosure suitable for surface mounting, and comes equipped with a 120 VAC piggyback power cord for simple plug-in installation.

Features

• Easy-to-read, bright, adjustable backlit LCD screen displaying temperature, parameters, and operational status.
• Simple three-button touchpad user interface for direct basic and advanced programming.
• Single-pole, double-throw (SPDT) output relay to control heating or cooling equipment.
• LED status indicator providing real-time visual feedback on the output relay status.
• Adjustable anti-short cycle delay to protect compressors from short cycling and hard starts.
• Temperature setback and sensor offset capabilities for custom scheduling and error correction.
• Restricted adjustment mode to lock parameters and prevent unauthorized user changes.

Specifications

• Supply Voltage: 120 VAC, 50/60 Hz
• Temperature Control Range: -40 to 212°F (-40 to 100°C)
• Power Consumption: 1.8 VA maximum
• Enclosure Rating: Type 4X (NEMA) / IP66 watertight, corrosion-resistant thermoplastic
• Input Signal: Includes an A99BB-200C PTC temperature sensor with a 6.6 ft. (2.0 m) cable
• Wiring Connections: Piggyback single power cord and plug combination

Applications

• On/off control of boilers, chillers, and heating/cooling systems.
• Temperature monitoring and alarming functions in commercial settings.
• Condenser fan and cooling tower fan control based on fluid or ambient temperatures.
• Control of supply, makeup, and mixed air temperatures in HVAC units.
• Temperature management for commercial refrigeration equipment such as walk-in coolers, display cases, and reach-in boxes.