The Johnson Controls P70AB-12 SPST Differential Pressure Control is designed to monitor and regulate pressure differences in HVAC and refrigeration systems. It operates by opening or closing a single-pole, single-throw electrical circuit based on preset differential pressure settings, ensuring proper system balance. Commonly used in chillers, air conditioning units, and refrigeration equipment, it helps protect compressors and maintain efficient operation. Its use enhances reliability, improves system safety, and reduces maintenance requirements, supporting consistent and efficient HVAC performance.