Johnson Controls P20DB-1 Pressure Control Differential Manual Reset A/C Limit, Open-High 100°F/425°F

The Johnson Controls P20DB-1 is a manual reset pressure control that is intended to protect residential and commercial air conditioning systems. It measures the pressure within the system and turns off the system if pressure rises beyond the set limit of pressure. This means that in normal operation the electrical contacts are closed and the air conditioner can run. However, if the pressure goes beyond the adjustable range of 100°F to 425°F, the contacts break, thereby cutting power to the compressor and stopping the system.