OEM Lennox Thermal Expansion Valve (TXV) — 42W43

The genuine OEM Lennox 42W43 thermal expansion valve (TXV) precisely meters the flow of refrigerant into the evaporator coil, regulating superheat so your Lennox system achieves rated cooling capacity and efficiency. By adjusting refrigerant flow to match the actual load, a properly functioning TXV protects the compressor and keeps the whole refrigeration cycle balanced.

When a TXV fails or clogs, you'll often notice reduced or uneven cooling, a frozen or iced-up evaporator coil, hissing sounds near the valve, higher-than-normal energy bills, or short-cycling on high or low pressure. A valve stuck open or closed disrupts superheat control and can put the compressor at risk if left unaddressed.

Choosing the OEM 42W43 matters because expansion valves are matched to a specific refrigerant type, tonnage, and superheat range. An incorrect or generic valve can overfeed or starve the coil, hurting performance and reliability. This factory-correct replacement ensures the right metering characteristics and a proper fit so your Lennox system cools efficiently and dependably.