A421AED-01C Johnson Controls Temperature Control

Overview

The Johnson Controls A421AED-01C is a line-voltage, single-stage electronic temperature control designed with an integrated off-cycle defrost timer and a single-pole, double-throw (SPDT) output relay. It features a bright, adjustable backlit LCD screen and a user-friendly three-button touchpad interface for seamless configuration. Enclosed in a rugged NEMA 4X watertight and corrosion-resistant housing, this unit is engineered for reliable surface-mount installation in challenging environments. It comes complete with a factory-included A99BB-25C temperature sensor featuring a 9 7/8-inch lead.

Features

• Off-Cycle Defrost Control: Configurable passive defrost periods spanning 1 to 99 minutes with an adjustable interval frequency from 2 to 24 hours.
• Backlit LCD Screen: High-visibility display with adjustable brightness levels and descriptive custom status icons.
• Programming Interface: Simple three-button touchpad featuring standard and advanced programming menus, alongside an optional restricted adjustment mode to avoid unauthorized tampering.
• Relay Protection: Integrated adjustable anti-short cycle delay prevents short cycling, hard starts, and premature compressor degradation.
• Temperature Adaptation: Supports switch-activated temperature setback via a binary input circuit, custom sensor offset adjustments for long wire leads, and sensor failure operation modes.
• Robust Enclosure: Heavy-duty, high-impact thermoplastic NEMA 4X (IP66/IP67) enclosure ensures watertight, weatherproof security.

Specifications

• Supply Voltage: 120/240 VAC, 50/60 Hz
• Power Consumption: 1.8 VA Maximum
• Temperature Control Range: -40°F to 212°F (-40°C to 100°C)
• Temperature Accuracy: Less than +/- 1.8°F (+/- 1.0°C)
• Differential Range: 1°F to 30°F
• Output Relay: Single-pole, double-throw (SPDT) dry-contact relay
• Contact Ratings: 15 A resistive at 120 VAC; 10 A resistive at 240 VAC; 1 hp motor rating at 120/240 VAC
• Sensor Type: A99BB-25C positive temperature coefficient (PTC) temperature sensor with a 9 7/8-inch (0.25 m) PVC cable
• Operating Ambient Temperature: -40°F to 140°F (-40°C to 60°C)
• Ambient Humidity: 0% to 95% RH non-condensing
• Enclosure Rating: NEMA 4X, IP66/IP67 watertight surface mount
• Dimensions: 5 inches Height x 2-3/8 inches Width x 2-3/8 inches Depth

Applications

• Commercial Refrigeration: Ideal for controlling walk-in coolers, reach-in display cases, and food service beverage boxes requiring scheduled defrost cycles.
• HVAC Equipment: Used for the on/off sequencing of commercial chillers, chiller pumps, space heating systems, and cooling exhaust fans.
• Industrial Process Control: Suitable for boilerplate temperature regulation, damper actuator control, and automated environmental monitoring systems requiring high-moisture defense.