Johnson Controls P145NCB-12 Pressure Control

As a seasoned technician, you know that keeping a compressor's lubrication system in check is non-negotiable. The Johnson Controls P145NCB-12 is a heavy-duty lube oil pressure cutout control with alarm specifically engineered for pressure-lubricated refrigeration compressors. This electromechanical workhorse measures net oil pressure—the critical difference between oil pump discharge and crankcase pressure—to ensure your bearings never run dry. It features a factory-set 120-second time delay, which is ambient-compensated to minimize nuisance tripping during cold starts while providing a reliable window for pressure to stabilize. With a fixed 9 PSI differential and a robust 425 PSIG maximum bellows pressure rating, this control is built for the high-demand environments of industrial and commercial HVACR systems. The 1/4" male flare pressure connection facilitates a secure fit, and the manual reset ensures a technician must inspect the system before restarting, preventing repeated startups under low-oil conditions. It is the designated replacement for legacy models including the P45NCA-46, P145NCA-12, and P45NCA-54.

• Dual-Voltage Versatility: Designed to operate on both 120/240 VAC circuits, making it a flexible choice for various motor starter configurations.
• Integrated Alarm Circuit: Features a dedicated terminal for remote monitoring, allowing you to wire an external lube oil pressure alarm for immediate fault notification.
• Fail-Safe Trip-Free Reset: The manual reset mechanism is trip-free, meaning it cannot be overridden by holding the button down, ensuring true system protection.
• Precise Pressure Sensing: Utilizes time-tested bellows technology to maintain a 9 PSI fixed differential for consistent performance across non-corrosive refrigerants.
• Reduced Nuisance Trips: The thermal time delay relay is compensated for temperature variations between 0°F and 131°F, ensuring the 120-second interval remains accurate in various mechanical room conditions.

What is the best way to connect this to the compressor?
For optimal vibration resistance and to minimize pressure pulsations, we recommend using SEC99AB-24 armored capillary tubes (Qty 2 usually required for most installs) to connect the 1/4" flare fittings to the oil pump and crankcase ports.

Can I adjust the 9 PSI setpoint in the field?
No, the P145NCB-12 is factory-set to the compressor manufacturer's specifications. If your application requires an adjustable range, you would typically look at the P128 series, though this fixed model is preferred for many OEM replacements to prevent field tampering.

How do I test the time delay circuit during a maintenance call?
You can manually trip the control using a small screwdriver to verify the 120-second heater cycle. This confirms the 120/240 VAC heater and the SPDT switch are functioning before leaving the job site.

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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.