Johnson Controls A19AAA-49 Utility Thermostat

The Johnson Controls A19AAA-49 Utility Thermostat is a technician-grade single-pole, single-throw (SPST) control designed for heavy-duty HVAC/R applications. Engineered to open on temperature drop, this low-limit control is essential for preventing freeze-ups in refrigeration systems and maintaining setpoint integrity in walk-in coolers and industrial storage units. It features a wide temperature range of -30°F to 100°F (-34°C to 38°C), making it a versatile component for both heating and cooling limit functions.

The A19AAA-49 is equipped with a 6-foot capillary tube, providing enough reach for remote sensing in hard-to-access coils or ducts. The liquid-filled sensing element ensures a rapid and accurate response to thermal shifts, while the rugged housing stands up to the vibration and moisture typical of commercial mechanical rooms. Whether you are performing a field replacement or a new system integration, this Johnson Controls thermostat offers the reliable mechanical switching required for high-stakes environmental control.

Key Benefits for Contractors

• Versatile Range: Spans from deep freeze levels to ambient temperatures (-30°F to 100°F) for broad application compatibility.
• Precise Switching: SPST open low action ensures reliable circuit interruption when temperatures fall below the adjustable setpoint.
• Flexible Installation: The 6' capillary allows for the control box to be mounted away from the sensing point for easier accessibility.
• Industrial Durability: Built with a focus on long-term mechanical life in demanding refrigeration and HVAC environments.
• Simplified Wiring: Standard terminal layout allows for quick installation and integration with existing contactors or relays.

Common Questions

What is the difference between open-on-rise and open-on-drop?
The A19AAA-49 is an open-on-drop (open low) control. This means the electrical circuit breaks when the temperature falls to the setpoint, typically used to shut down a compressor or cycle a heater to prevent over-cooling.

Can the differential be adjusted on this model?
This specific utility thermostat is designed with a fixed or narrow differential to maintain tight control over the environment without excessive equipment cycling.

Is this thermostat suitable for walk-in freezers?
Yes, the -30°F lower limit makes it an ideal candidate for low-limit protection or temperature control in commercial walk-in freezers and cold storage units.

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.