Lennox 12J43 TXV

The Lennox 12J43 Thermal Expansion Valve (TXV) is a critical metering component engineered specifically for 2-ton residential and commercial R410A refrigerant systems. This OEM Lennox expansion valve features a 3/8" ODM (Outside Diameter Male) inlet and a 1/2" ODF (Outside Diameter Female) outlet, ensuring a precise fit for outdoor NXT units and matching indoor coils. By continuously monitoring evaporator superheat, the 12J43 TXV regulates refrigerant flow to prevent liquid slugging and evaporator icing, protecting the compressor from premature mechanical failure.

Designed for high-pressure HFC-410A applications, this thermostatic expansion valve maintains optimal heat transfer across the coil, even under fluctuating ambient temperatures. For veteran technicians, this means more stable subcooling readings and improved system SEER ratings during peak demand. The robust brass construction and high-grade sensing bulb provide the durability required for rigorous field conditions. When replacing this Lennox 2-ton TXV, always install a new liquid line filter drier to maintain system chemistry and prevent debris from fouling the internal orifice.

Key Benefits

• Precise Refrigerant Control: Optimizes R410A flow to maximize cooling capacity and system efficiency.
• OEM Compatibility: Genuine Lennox 12J43 (103366-15) part ensures seamless integration with 2-ton HVAC units.
• System Protection: Effectively prevents compressor damage by modulating flow based on real-time load requirements.
• Field-Proven Reliability: Heavy-duty brass valve body and hermetically sealed sensing bulb for long-term outdoor use.

Common Questions

Is the Lennox 12J43 compatible with R-22 systems?
No, this specific model is calibrated strictly for R410A refrigerant pressures and cannot be used in R-22 or R-454B applications.

Does this TXV require a hard start kit?
If the outdoor unit utilizes a reciprocating compressor, a hard start kit is highly recommended to assist with startup torque against the pressure differential maintained by the non-bleed TXV.

What is the correct sensing bulb position?
On suction lines smaller than 7/8", the bulb should be secured at the 10 o'clock or 2 o'clock position on a horizontal run, at least 4 inches from the braze joint.

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.