Johnson Controls P29NA-3 Cutout Control

The Johnson Controls P29NA-3 Cutout Control is a field-proven low pressure cutout control designed for commercial refrigeration and HVAC systems. Frequently used as a primary safety control, the P29NA-3 prevents compressor damage by monitoring suction pressure and initiating a time delay relay before shutdown. This unit operates on a 24 Vac control circuit and features an auto recycle function, allowing the system to resume operation once pressure stabilizes within the 20" Hg to 100 PSIG setpoint range. The P29NA-3 is technically identical to the P29NA-3C model, ensuring seamless cross-compatibility for service replacements. Its low pressure switch logic provides precise refrigeration pressure regulation, crucial for protecting hardware against loss of charge or evaporator freeze-ups. Built with a robust bellows-actuated mechanism, this control minimizes nuisance tripping while maintaining tight tolerances in demanding environments.

Key Benefits for Technicians

• Integrated Time Delay: Reduces short-cycling by allowing momentary pressure fluctuations without disconnecting the compressor contactor.
• Broad Pressure Range: Adjustable from 20" Hg to 100 PSIG, making it versatile for various refrigerant low pressure cutouts.
• Automatic Reset: The auto recycle feature eliminates unnecessary site visits for manual resets after temporary pressure drops.
• Universal Compatibility: Direct replacement for the P29NA-3C, simplifying inventory management for contractors.
• Reliable 24V Operation: Specifically engineered for standard low voltage control circuits in commercial cooling applications.

Common Questions and Installation Insights

Is the P29NA-3 compatible with all HCFC and HFC refrigerants?
Yes, the bellows and internal components are designed for compatibility with non-corrosive refrigerants typically found in high and medium-temperature systems.

How do I test the time delay circuit during commissioning?
You can verify the delay by manually dropping the pressure below the cutout point while monitoring the 24V output to ensure the compressor remains energized for the rated delay period before the circuit opens.

Does this control require a manual restart after a low-pressure event?
No, this model is an auto-recycle control. Once the pressure rises above the cut-in differential, the internal switch closes automatically to resume cooling cycles.

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.