A pressure switch is a safety control device that opens or closes electrical circuits in response to refrigerant or air pressure changes. These switches protect HVAC equipment by preventing operation at unsafe pressure levels. Pressure switches typically include both low-pressure and high-pressure settings, with adjustable deadbands between activation and deactivation points.
Common Applications
High-pressure switches on air conditioning systems typically activate between 400 and 450 PSI to protect compressors from excessive pressure. Low-pressure switches engage between 30 and 50 PSI on cooling systems to prevent compressor damage from loss of refrigerant. Heat pump systems use low-pressure switches around 50 to 100 PSI to detect low refrigerant conditions or freezing coils.
Safety and Diagnostics
Pressure switches automatically shut down compressors when system pressures exceed safe operating ranges, preventing component damage and refrigerant leaks. Faulty pressure switches cause nuisance shutdowns or fail to protect equipment. Service technicians use pressure switch settings to diagnose system problems including refrigerant leaks, blockages, and compressor failures.