As a service tech

An open circuit (OL) indicates a failed internal element that requires immediate replacement

In most standard installations

If the system pressure is within 10% of the 80 PSI set pressure

Schneider Electric (Barber Colman) 2390-501 Gradual Switch Freon As a service techThe Schneider Electric 2390 501 Gradual Switch is a precision engineered pneumatic manual positioner designed for proportional control in commercial HVACR systems. Utilizing a reliable manual dial, this device allows technicians to modulate output pressure from 0 to 20 psig, providing direct control over pneumatic actuators, dampers, and valves. Built for durability and accuracy, the 2390 501 operates with a 20 psig main air pressure and delivers an 8