Description
Lennox 38M78 Low Ambient Pressure Switch Overview
The Lennox 38M78 is an OEM low ambient pressure switch engineered to protect refrigeration circuits during cold-weather operation. By monitoring system pressures and interrupting operation when conditions fall outside safe parameters, this switch helps prevent compressor damage and ensures reliable performance year-round.
Key Specifications
- SKU / Part Number: 38M78
- Cut-In (Make) Pressure: 450 PSI
- Cut-Out (Break) Pressure: 250 PSI
- Function: Low Ambient Pressure Switch
- OEM Lennox Replacement Part
How It Works
The low ambient switch senses refrigerant-side pressure and opens the circuit when pressure drops to the cut-out setpoint (250 PSI), preventing the system from operating under dangerously low-pressure conditions common in cold ambient temperatures. The switch automatically resets and closes the circuit once pressure recovers to the cut-in setpoint (450 PSI), restoring normal system operation without manual intervention.
Features & Benefits
- Protects compressor from low-pressure damage during cold ambient conditions
- Automatic reset — closes at 450 PSI cut-in, opens at 250 PSI cut-out
- Direct OEM Lennox replacement for accurate fit and reliable performance
- Helps maintain system efficiency and extend equipment service life
- Suitable for use in residential and light commercial Lennox refrigeration and air conditioning systems
Application
Designed as a direct OEM replacement for compatible Lennox air conditioning and heat pump systems. Always verify compatibility with your specific Lennox equipment model before installation. Consult Lennox documentation or a qualified HVAC technician for proper installation and wiring procedures.
