Johnson Controls A19AAB-4 Temperature Control

The Johnson Controls A19AAB-4 is a professional-grade mechanical temperature control designed for heavy-duty HVACR applications requiring high-precision single-stage temperature control. This robust remote bulb thermostat features a single-pole, single-throw (SPST) switch configuration that is factory-set to open on high temperature. Engineered with a liquid-filled sensing element, the A19AAB-4 provides consistent repeat accuracy that remains unaffected by barometric pressure or cross-ambient conditions, making it an ideal choice for refrigeration, space heating, and commercial ventilating systems.

Operating across a versatile 24 to 277Vac voltage range, this unit includes a 30 to 110?F setpoint range with a 3.5?F fixed differential to ensure stable cycling. The hardware includes a 6-foot capillary and a 3/8" x 5" copper sensing bulb, allowing for flexible remote mounting. For field security, the A19AAB-4 utilizes a screwdriver slot range adjuster with a visible scale, preventing unauthorized setpoint changes while allowing contractors to verify system parameters at a glance. The automatic reset mechanism ensures continuous operation without the need for manual intervention after a temperature cutout event.

• System Reliability: The liquid-filled sensing bulb ensures the Johnson Controls A19 series maintains calibration regardless of the ambient temperature surrounding the control case.
• High Compatibility: Universal SPST open-high action and wide AC voltage ratings (up to 277Vac) allow this part to serve as a drop-in replacement for various HVAC temperature controllers.
• Tamper Resistance: The screwdriver slot adjustment reduces nuisance calls by deterring end-user tampering with critical thermal settings.
• Precision Sensing: A 6' capillary length provides ample reach for immersion or air-stream sensing in localized refrigeration equipment or display cases.

• Can this be used for both heating and cooling? This model is specifically SPST Open High, meaning the contacts open as the temperature rises. It is primary used for heating cutout or high-limit applications.
• Does this control require a bulb well for immersion? While the 3/8" x 5" copper bulb can be used for air sensing, liquid immersion applications require a WEL14A-602R bulb well or FTG13A-600R packing nut (sold separately) to prevent leaks and protect the element.
• Is the differential adjustable? No, the A19AAB-4 is designed with a fixed 3.5?F differential to provide a standardized, non-adjustable switching window.

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.