Johnson Controls A11D-5 Temperature Control

The Johnson Controls A11D-5 is a professional-grade low temperature cutout freezestat designed for critical freeze protection in HVAC systems. Engineered for high-stakes applications, this mechanical temperature control monitors air or liquid temperatures and opens the SPDT switch when the temperature drops below the setpoint across any 1 foot of its 20-foot vapor-actuated sensing element. This specific model features a manual reset mechanism, ensuring that systems remain offline until a technician can inspect the coil and confirm conditions are safe for restart. Operating on a 24 to 277Vac range, the A11D-5 provides a cutout range of 35 to 45 degrees F with a 12 degree F fixed differential. The 4-foot capillary leads to the 1/8" x 20' sensing bulb, making it ideal for large duct cross-sections where stratified air could lead to localized coil freezing and subsequent equipment failure. For those cross-referencing parts, the A11D-5 is identical to A11D-5C.

• Sensing Coverage: The 20-foot sensing element detects the lowest temperature along any portion of its length, preventing localized "slugging" or coil bursts.
• System Reliability: Manual reset functionality prevents rapid cycling and ensures a diagnostic check occurs before system reactivation.
• Universal Voltage: Compatible with common control circuits from 24V to heavy-duty 277Vac industrial applications.
• Robust Construction: The vapor-actuated design is less susceptible to ambient temperature fluctuations at the control head compared to liquid-filled units.

Can this freezestat be mounted in any orientation?
Yes, the control head can be mounted in any position, but for optimal freeze protection, the 20-foot sensing element must be distributed horizontally across the downstream side of the coil to ensure full-face coverage.

How does the SPDT contact configuration function in this model?
The SPDT switch allows you to simultaneously break the circuit to the fan motor or compressor (normally closed) and energize an alarm or indicator light (normally open) upon a low-temperature trip.

What is the difference between the A11D-5 and the A11D-5C?
There is no functional or technical difference; the A11D-5 and A11D-5C are the same unit and can be used interchangeably in all HVACR control applications.

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.