Johnson Controls P70MA-1 Pressure Control

The Johnson Controls P70MA-1 Pressure Control is a heavy-duty dual pressure switch engineered for precision monitoring in commercial refrigeration and air conditioning systems. This SPST switching control serves as the direct replacement for the 2891550, providing a versatile "all-range" solution for systems utilizing R-12, R-22, R-134A, R-500, and R-502 refrigerants. It features a low-pressure side adjustable from 20" Wc to 100 psi with a 7 to 50 psi differential, paired with a high-pressure side ranging from 100 to 500 psi. To ensure equipment safety during critical overpressure events, the high-pressure side includes a manual reset lockout mechanism. Built with a rugged steel case and a 36" capillary with 1/4" flare nut, the P70MA-1 allows for MICRO-SET accuracy and external adjustability without needing to remove the cover, streamlining field service and calibration for HVACR technicians.

Key Benefits for Contractors

• Universal Compatibility: Designed for use with all standard non-corrosive refrigerants, reducing the need to carry multiple specialized controls on the truck.
• High-Pressure Safety: The manual reset lockout ensures that technicians must inspect the system before restarting, preventing damage from repeated high-head pressure cycles.
• Precise Calibration: Features MICRO-SET differential adjustments for fine-tuning low-pressure cut-in and cut-out points.
• Field Durability: Housed in a NEMA 1 high-strength steel enclosure to withstand demanding mechanical room environments.
• Ease of Installation: The 36-inch capillary provides flexibility for mounting while the 1/4" flare nut simplifies connection to the high and low-side ports.

Common Questions

Is the P70MA-1 compatible with R-410A systems?
While the P70MA-1 handles up to 500 psi on the high side, it is primarily optimized for older "all-range" refrigerants. For high-pressure R-410A applications requiring higher burst pressure ratings, verify specific system requirements against the 500 psi limit.

What is the difference between SPST and SPDT in these controls?
The P70MA-1 uses SPST (Single-Pole Single-Throw) switching, which opens or closes a single circuit on pressure rise or fall. This is standard for straightforward compressor or fan cycling applications.

Does this unit require a specific mounting orientation?
For best performance and to prevent oil logging in the capillary, it is recommended to mount the control vertically with the pressure connections facing downward.

This item is not eligible for free shipping.

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.