Johnson Controls A421ABG-02 Temperature Control

The Johnson Controls A421ABG-02 is a professional-grade single-stage electronic temperature control designed for versatile HVACR applications. Operating on 120V AC, this unit features a factory-installed 6-foot power cord with a grounded male plug and a 6-foot cord with a female outlet, simplifying "plug-and-play" integration for refrigeration and heating equipment. As the direct cross version of A419ABG-3, the A421 series represents the next generation of PENN temperature controllers, offering enhanced digital precision and an intuitive three-button touchpad interface. The unit provides a broad control range of -40 to 212?F (-40 to 100?C) and includes a high-accuracy A99BB-200C temperature sensor with a 6.6-foot cable. The SPDT output relay allows for seamless switching between heating and cooling modes, while the backlit LCD ensures clear visibility of setpoints and relay status in low-light mechanical rooms. Built into a NEMA 1 high-impact plastic enclosure, it supports both surface and DIN rail mounting, making it a reliable digital thermostat replacement for technicians requiring fast setup and consistent performance.

• Direct Cross Compatibility: Engineered as the primary replacement for the legacy A419ABG-3 series with improved digital logic.
• Integrated Protection: Features an adjustable anti-short cycle delay (0?12 minutes) to prevent compressor short-cycling and extend equipment life.
• Advanced Operational Control: Includes sensor offset for calibration and temperature setback functionality via a binary input for energy-saving cycles.
• Rugged Reliability: Housed in a durable NEMA 1 enclosure designed to withstand standard mechanical room environments and surface mount or DIN rail configurations.

How do I switch the A421ABG-02 between heating and cooling modes?
The mode is determined by the relationship between the "On" and "Off" setpoints. If the "On" temperature is higher than the "Off" temperature, the control operates in cooling mode. If the "On" temperature is lower than the "Off" temperature, it operates in heating mode.

Can the temperature sensor cable be extended for remote monitoring?
Yes, the A99 temperature sensor leads can be extended up to 250 feet using 22 AWG shielded cable, provided the connections are secure and the sensor offset parameter is adjusted to compensate for any added resistance.

What happens if the sensor fails during operation?
The A421 series allows technicians to pre-set a Sensor Failure Mode, enabling the relay to remain in either a constant "On" or "Off" state to protect sensitive inventory or equipment until the sensor is replaced.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.