Carrier 331709-757 TXV Kit

When you're dealing with a 4 to 5-ton Carrier, Bryant, or Payne residential unit that isn't maintaining superheat, the Carrier 331709-757 TXV Kit is the specified OEM solution for R-410A refrigerant circuits. This thermostatic expansion valve (TXV) is a high-precision metering device engineered to modulate refrigerant flow into the evaporator coil based on heat load, preventing liquid slugging and protecting the compressor. As a hard-shutoff TXV, it maintains a tight seal during the off-cycle, which is critical for systems utilizing scroll compressors to prevent pressure equalization issues. The kit includes the valve body with 3/8-inch fittings, a sensing bulb with a mounting strap, and a Teflon washer for a leak-free mechanical connection. Integrating this genuine Carrier replacement part ensures your refrigerant flow regulation meets factory specifications, optimizing HVAC system efficiency and ensuring consistent evaporator coil performance under fluctuating ambient conditions. For contractors, this provides a drop-in OEM HVAC part that restores the original subcooling and superheat parameters required for peak system longevity.

• Precise Superheat Control: Automatically adjusts refrigerant flow to maintain the ideal superheat, preventing coil freeze-ups and compressor damage.
• R-410A Compatibility: Specifically calibrated for high-pressure R-410A systems with a 4 to 5-ton capacity range.
• Simplified Installation: Features standard 3/8-inch mechanical fittings and includes the necessary bulb straps and Teflon seals for a secure fit.
• OEM Performance: Meets exact Carrier factory authorized parts specifications for reliability in demanding residential cooling applications.

Is a hard start kit required with this TXV?
Because this is a hard-shutoff valve, it may require the installation of a hard start kit—especially on systems with reciprocating compressors—to provide the necessary torque to start against unequalized pressures.

Can this kit be used to convert an orifice system to a TXV?
Yes, this TXV conversion kit is frequently used to upgrade older piston-style metering devices to improve SEER ratings and humidity removal, provided the evaporator coil is compatible with the 3/8-inch fittings.

Where should the sensing bulb be mounted?
For optimal refrigerant metering, the bulb must be mounted on a horizontal run of the suction line at the 3 o'clock or 9 o'clock position, at least 4 inches from the braze joint, and insulated to sense true line temperature.

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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.