Johnson Controls A70HA-2 Temperature Control

The Johnson Controls A70HA-2 is a heavy-duty single pole temperature control engineered for high-limit cutout applications in both refrigeration and heating systems. Operating within a 35°F to 80°F temperature range, this controller features a critical open low action with a lockout manual reset mechanism, ensuring system safety by preventing automatic restarts after a limit trip. The unit is equipped with a 6-foot capillary for flexible sensing bulb placement and includes a reverse acting auxiliary contact to trigger alarm circuits or secondary indicators when the main contacts open. Designed for 120-240 Vac electrical service, the rugged enclosure provides a 1/2" conduit opening for secure high-voltage wiring. This HVAC high limit switch is a standard solution for contractors requiring reliable freeze protection or low-temperature cutout functionality in commercial environmental equipment.

Key Benefits for Technicians:

• Manual Reset Safety: Prevents equipment damage by requiring a physical inspection before restarting the system after a low-limit event.
• Versatile Electrical Compatibility: The SPST switch handles 120V or 240V circuits, making it compatible with various commercial refrigeration controls.
• Auxiliary Signaling: Integrated reverse-acting contact allows for immediate remote monitoring or fault light activation.
• Durable Capillary Design: The 72-inch capillary provides ample length for proper bulb positioning in air streams or liquid lines.
• Field-Proven Reliability: Built for demanding environments where precision temperature sensing is required to maintain system integrity.

Technical FAQ:

How does the manual reset function on the A70HA-2?
When the sensed temperature drops to the cutout setpoint, the A70HA-2 opens the main circuit and locks. The system will stay disabled until the temperature rises above the setpoint and the reset button is manually depressed by a technician.

What is the purpose of the reverse acting auxiliary contact?
The auxiliary contact operates opposite to the main terminals. When the main circuit opens (cutting power to the compressor or heater), the auxiliary circuit closes, which is typically used to energize an alarm circuit or a Building Management System (BMS) input.

Can this control be used for both heating and cooling applications?
Yes, while it is commonly used as a low temperature cutout in HVAC coils to prevent freezing (freeze-stat), it is rated for any HVACR application within its electrical and thermal specifications where an open-low action is required.

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.