Lennox 99K64 Air Sensor

The Lennox 99K64 is a professional-grade discharge/return air sensor designed for precision temperature monitoring in commercial and residential HVAC applications. This 10k ohm NTC thermistor provides critical data to the Prodigy Unit Controller and Network Thermostat Controller, ensuring accurate thermal management within the supply or return air streams. Featuring a 12-inch stainless steel probe and a secure two-screw mounting plate, the 99K64 air sensor is engineered for high stability and an interchangeability accuracy of +/-0.36°F. It is a vital component for systems operating in Discharge Air Control (DAC) mode, acting as a reliable backup to zone sensors and enabling essential return air limit functions. This OEM Lennox replacement part ensures seamless integration with LGM, LGH, and Energence series units, maintaining the tight tolerances required by veteran technicians for optimal system staging and airflow efficiency.

• Precise Monitoring: The 10,000 Ohm resistance element at 77°F provides highly accurate feedback for discharge and return air staging.
• Durable Construction: The 12-inch probe is built from stainless steel to withstand high-velocity airflow and harsh duct environments.
• Enhanced Compatibility: Fully compatible with Lennox M2, M3, and M4 unit controllers for advanced zoning and network applications.
• System Redundancy: Provides a critical failsafe by acting as a backup if the primary zone sensor or wiring fails.
• Easy Installation: The non-polarity sensitive 2-wire lead design simplifies field wiring to NTC terminals.

Where should the 99K64 sensor be installed for the best accuracy?
For discharge air applications, install the sensor in the supply duct, ideally after a 90-degree turn, to ensure the probe measures a mixed air temperature rather than a localized hot or cold spot.

What is the maximum wire length for this sensor?
When using 18 AWG wire, the maximum recommended cable length is 25 feet to prevent signal degradation and maintain temperature accuracy.

Does this sensor require specific polarity when wiring to the controller?
No, the Lennox 99K64 is a resistive NTC thermistor and is not polarity sensitive, allowing for straightforward connection to the unit controller terminals.

This item is not eligible for free shipping.

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.