Johnson Controls A19ZBC-2 Temperature Control

For industrial refrigeration specialists managing commercial display cases, the Johnson Controls A19ZBC-2 provides a reliable electromechanical solution for integrated defrost termination and fan delay. This remote bulb mechanical temperature control is engineered with a single-pole, double-throw (SPDT) switch configuration, allowing for precise transitions between defrost cycles and regular cooling operations. The A19ZBC-2 features a factory-preset fan delay of 25°F (-4°C), ensuring that evaporator fans do not circulate warm, moist air immediately after a defrost cycle. The sensing element is specifically designed to remain unaffected by barometric pressure or cross-ambient temperature fluctuations, maintaining calibration in high-demand environments.

The unit utilizes a 6-foot capillary and a 19/64" x 3 1/8" sensing bulb to monitor coil temperatures effectively. With a setpoint range of 45°F to 85°F (7°C to 29°C), technicians can fine-tune the defrost duration via the external knob range adjuster. This control is compatible with systems ranging from 24 to 277Vac and includes an automatic reset function for unattended operation. The rugged construction and automatic reset capability make it a staple for maintaining efficiency in electric defrost and hot gas defrost systems.

• Versatile Application: Dual-functionality handles both defrost termination and fan delay in a single SPDT temperature control.
• Stable Calibration: The liquid-filled sensing bulb ignores ambient temperature shifts, providing consistent performance regardless of where the case is located.
• Electrical Compatibility: Broad voltage support from 24Vac to 277Vac makes it a universal replacement part for various HVACR refrigeration setups.
• Field Serviceable: Simple knob range adjuster allows for quick on-site calibration of defrost termination settings without specialized software.

How do I adjust the fan delay on the A19ZBC-2?
The fan delay is factory-set at 25°F (-4°C). While the defrost termination is adjustable via the knob, the fan delay is pre-calibrated to optimize refrigeration cycle efficiency.

What is the maximum bulb temperature for this unit?
The sensing bulb can withstand temperatures up to 140°F (60°C). Exceeding this limit may damage the sensing element or affect calibration accuracy.

Can this control be used for both electric and hot gas defrost?
Yes, the Johnson Controls A19ZBC-2 is designed to work with both electric heat and hot gas defrost initiation systems when paired with a standard defrost timer.

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.