Johnson Controls A70HA-1 Temperature Control

The Johnson Controls A70HA-1 is a commercial-grade, low-limit temperature control engineered for critical refrigeration and heating applications. Designed with a vapor pressure sensing element and a 20-foot capillary, this controller provides precise monitoring across a 15°F to 55°F range. As a manual reset temperature switch, it prevents automatic equipment restarts after a low-temperature cutout, ensuring a technician can inspect the system before resuming operation. The unit features SPDT contacts with a reverse-acting auxiliary contact, allowing the main circuit to open while simultaneously closing a secondary circuit for an alarm or indicator light when the temperature drops to the setpoint.

This control is the technician’s choice for freeze protection in air handling units (AHUs) and coil monitoring. With a 1/2-inch conduit opening and high electrical ratings for 120/240 VAC applications, it integrates seamlessly into existing wiring configurations. The A70HA-1 serves as the direct replacement for the 2284-900 and A19AAC-1, offering a rugged mechanical temperature control solution that handles overruns up to 400°F without calibration drift.

Key Benefits for Contractors:

• System Safety: Manual reset lockout ensures equipment stays offline until conditions are safe, preventing compressor slugging or coil ruptures.
• Extended Reach: The 20-foot capillary allows for extensive coil coverage or flexible mounting in large walk-in coolers and HVAC plenums.
• Versatile Wiring: SPDT snap-acting switches support both heating and cooling safety logic, including reverse acting auxiliary contacts for remote monitoring.
• Industrial Durability: Mechanical design eliminates the need for external power to the sensor, providing reliable operation in harsh environments.
• Application Accuracy: Factory-set stop at 35°F and a fixed 5°F differential ensure a tight response to low-temperature excursions.

Common Questions:

Can the A70HA-1 be used for both refrigeration and heating?
Yes, the single-pole, double-throw (SPDT) switch allows you to wire the control to open the circuit on temperature drop for cooling safeties or close a circuit for heating/alarm applications.

How does the manual reset function work?
When the sensed temperature falls below the setpoint, the main contacts lock in the open position. The system will not restart until the temperature rises above the differential and the reset button is manually depressed by a technician.

What are the direct replacements for this model?
The A70HA-1 is the current replacement for the Johnson Controls 2284-900 and the A19AAC-1, utilizing the same mounting footprint and technical specifications.

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.