Lennox 78L19 Expansion Valve

Proper refrigerant metering is the backbone of any reliable HVACR system, and the Lennox 78L19 Expansion Valve is a critical component for maintaining precise superheat. Designed for high-performance residential and light commercial equipment, this Thermostatic Expansion Valve (TXV) is chemically compatible with both R-410A and R-22 systems. The 78L19, which is identical to 78L1901, features a durable brass body with threaded connections, making it a drop-in HVAC replacement part for many Lennox evaporator coils. By accurately regulating liquid refrigerant flow into the evaporator, this Lennox TXV prevents liquid slugging and ensures the compressor operates within safe parameters. Field-proven reliability and thermal responsiveness make the 78L19 expansion valve the preferred choice for service technicians seeking to restore factory-spec efficiency. Whether you are addressing a stuck TXV or performing a full system overhaul, utilizing this OEM Lennox part ensures compatibility and long-term stability under varying thermal loads.

• System Stability: Maintains optimal superheat levels to maximize heat transfer across the evaporator coil.
• Universal Compatibility: Engineered as a direct replacement for 78L1901, ensuring a perfect fit in existing Lennox configurations.
• Rugged Construction: Built with high-grade brass to resist corrosion and withstand high-pressure environments.
• Compressor Protection: Actively prevents refrigerant floodback, a primary cause of premature compressor failure.
• Precision Metering: Responds rapidly to pressure and temperature changes for consistent cooling performance.

Is the 78L19 compatible with R-410A systems?
Yes, this valve is designed to handle the higher pressures of R-410A refrigerant while maintaining accurate flow control.

Can I use this valve if my current part number is 78L1901?
Absolutely. The 78L19 is the current replacement and is technically identical to the 78L1901 part number.

What are the signs of a failing expansion valve?
Technicians typically look for frost on the evaporator, high superheat readings, or the system "hunting" (rapidly fluctuating suction pressure), which indicate the valve is no longer metering correctly.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.