A421AET-01C Johnson Controls Temperature Control

Overview

The Johnson Controls A421AET-01C is a single-stage electronic temperature control featuring a single-pole, double-throw (SPDT) output relay and an integrated cycle timer. Designed for precise temperature management, it includes a bright backlit LCD screen and an intuitive three-button touchpad interface. It comes equipped with a Type 4X (NEMA) / IP66 watertight, corrosion-resistant enclosure suitable for surface-mount installations, making it highly durable for challenging environments.

Features

• High-visibility backlit LCD with adjustable brightness for convenient monitoring.
• Three-button touchpad interface for simple configuration and option restriction.
• Integrated On/Off duty-cycle timer for specialized ventilation or cooling controls.
• Adjustable anti-short cycle delay to protect compressors and HVAC equipment from rapid cycling.
• Temperature setback and sensor offset capabilities for tailored operation.
• LED indicator displaying the real-time On/Off status of the output relay.
• Keypad lockout functionality to prevent unauthorized adjustment changes.

Specifications

• Temperature Control Range: -40 to 212°F (-40 to 100°C)
• Supply Voltage: Line-voltage model rated for 120/240 VAC, 50/60 Hz
• Relay Output: Single-pole, double-throw (SPDT)
• Power Consumption: 1.8 VA maximum
• Enclosure Rating: NEMA Type 4X / IP66 watertight, high-impact thermoplastic
• Included Sensor: A99BB-25C positive temperature coefficient (PTC) sensor with a 9-7/8 inch (0.25 m) PVC cable

Applications

• On/off control of commercial boilers, chillers, and associated pump logic.
• Automated heating and cooling equipment regulations across diverse HVAC configurations.
• Floating temperature controls for dampening equipment and commercial valve actuators.
• Defrost cycle controls and cooling tower fan operations based on exact liquid temperatures.
• Industrial temperature monitoring, alerting, and general facility climate oversight.