The switch closes its contacts at 450 PSI to start the condenser fan and opens them at 250 PSI to stop the fan

This OEM Nordyne furnace part is engineered for high-performance heat transfer

a normally open solenoid valve like the 8214G23-24V serves as the vent valve

and ZR48K3-PFV-235

Maxitrol EFP-1 Cover Plate Only R-410A The switch closes its contactsProfessionals in the field understand that maintaining the external interface of control systems is non negotiable for system longevity. The Maxitrol EFP 1 Cover Plate is the specific replacement cover plate designed for seamless integration with the Maxitrol TD114, TD120, and TD121 remote temperature selectors. Engineered as a flush mount wall plate, this component ensures that the internal electronics of your HVAC temperature control interface