A421AED-02C Johnson Controls Temperature Control

Overview

The Johnson Controls A421AED-02C is a line-voltage, single-stage electronic temperature control designed with an integrated off-cycle defrost timer. Housed in a NEMA 4X (IP66) watertight and corrosion-resistant enclosure suitable for surface mounting, this control features a backlit LCD interface with a three-button touchpad. It provides reliable temperature management and automated passive defrost cycles, utilizing a remote A99BB-200C PTC temperature sensor with a 6.6-foot lead.

Features

• Single-stage temperature control with an SPDT output relay rated at 8 Amps at 240 Volts.
• Integrated off-cycle defrost timer allows programmable passive defrost periods from 1 to 99 minutes with intervals from 2 to 24 hours.
• Bright, adjustable backlit LCD screen displaying current temperature, parameter codes, and system status icons.
• Three-button touchpad programming interface with optional restricted user adjustment mode.
• Adjustable anti-short cycle delay (0 to 12 minutes) to prevent compressor short cycling and hard starts.
• Binary input circuit for switch-activated temperature setback/offset control.
• Sensor failure action setting to either run continuously or shut down safely.

Specifications

• Supply Voltage: 120/240 VAC, 50/60 Hz
• Power Consumption: 1.8 VA maximum
• Temperature Control Range: -40 to 212°F (-40 to 100°C)
• Temperature Differential: 1 to 30°F
• Sensor Type: A99BB-200C PTC sensor (1,035 ohm at 77°F) with 6.6 ft (2.0 m) cable
• Sensor Offset Range: ±5°F (±3°C)
• Enclosure Rating: Type 4X (NEMA), IP66 watertight, corrosion-resistant thermoplastic
• Operating Ambient Temperature: -40 to 140°F (-40 to 60°C)
• Compliance: cULus Listed, CE, RCM, FCC Compliant

Applications

• Ideal for medium-temperature cooling applications such as reach-in boxes, display cases, and walk-in coolers requiring timed, passive defrost cycles.
• Suitable for general single-stage refrigeration or HVAC systems including on/off chiller control and chiller pump control.
• Designed for demanding washdown or outdoor environments requiring watertight surface mount protection.