Johnson Controls P128AA-17 Oil Control

The Johnson Controls P128AA-17 is a specialized electromechanical lube oil control designed to safeguard pressure-lubricated refrigeration compressors from terminal damage. Functioning as a direct replacement for the P28AA-43, this unit accurately monitors net oil pressure by calculating the differential between the oil pump discharge and the compressor crankcase. It features dual 1/4" SAE flare connectors, eliminating the need for capillary tubing and reducing common leak points in the field. The adjustable cut-out pressure range of 8 to 70 PSI allows technicians to fine-tune the setpoint to meet specific OEM compressor requirements, ensuring high-performance protection across various non-corrosive refrigerants, including R-22, R-134A, and R-404A.

For reliable operation during startup, the P128AA-17 oil pressure switch incorporates an ambient-compensated 120-second time delay. This delay prevents nuisance tripping caused by momentary pressure fluctuations while allowing sufficient time for oil pressure to stabilize. The trip-free manual reset mechanism ensures that the system cannot be restarted until the technician addresses the underlying lubrication issue, providing a critical layer of safety for semi-hermetic and hermetic systems. This 120/240 VAC control is an industry standard for professional contractors seeking a rugged, field-adjustable solution for oil failure protection.

• Universal Compatibility: Direct replacement for P28AA-43 and compatible with most HVAC compressor protection sequences.
• Precise Pressure Monitoring: Measures differential oil pressure specifically to prevent bearing seizure and mechanical failure.
• Enhanced Reliability: The 120-second heater circuit is temperature-compensated to maintain accurate timing in varying mechanical room conditions.
• No Capillary Needed: Integral SAE flare connections streamline installation and minimize vibration-related piping failures.

• How do I set the cutout pressure? Use the internal adjusting disk to align the pointer with the desired PSI on the visible scale based on the manufacturer’s net oil pressure spec.
• Will this work with 240V systems? Yes, the heater circuit is rated for both 120V and 240V AC applications.
• What is the difference between the P128 and P28 series? The P128 series features 1/4" male flare connections, whereas the P28 typically utilizes capillary tubing.

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.