Lennox 28W70 Defrost Sensor

The Lennox 28W70 Defrost Sensor w/Harness is a critical OEM replacement component designed to maintain optimal efficiency in Lennox heat pumps and refrigeration systems. This 50-inch wiring harness with defrost sensor assembly includes a high-precision thermistor that monitors evaporator coil temperatures to prevent excessive frost accumulation. Engineered for a seamless fit, the Lennox 101334-01 ensures the defrost control board receives accurate data to trigger the defrost cycle at the precise moment, protecting the compressor and preventing system-wide freeze-ups. This 24AWG harness features high-conductivity leads and a robust 3-lead configuration for reliable temperature sensing across multiple points.

For technicians servicing Lennox XP16 or XP19 series units, this genuine Lennox 28W70 sensor provides the exact resistance values required by the microprocessor-driven defrost control. Replacing a worn or open-circuit sensor with this factory-assembled harness restores communication between the sensors and the control board, eliminating common performance issues like short-cycling or thermal lockout during extreme weather conditions.

• Direct OEM Compatibility: Specifically calibrated for Lennox heat pumps, ensuring accurate thermistor resistance (10k ohms at 77°F) for precise cycle control.
• Comprehensive Monitoring: Integrates sensors to track coil and ambient conditions, essential for maintaining SEER efficiency ratings.
• Robust Build: Includes a 50-inch harness with standard 24-gauge wiring for easy routing through the cabinet to the control board terminals.
• System Protection: Actively prevents ice buildup on coils, which reduces physical strain on the blower motor and compressor.

What are the symptoms of a failing defrost sensor?
A faulty Lennox defrost sensor often causes the outdoor unit to become a solid block of ice or prevents the system from entering defrost mode. You may also see the unit stuck in the defrost cycle indefinitely, leading to inefficient heating performance.

How do I test the Lennox 28W70 sensor?
Technicians should check for continuity and resistance across the leads using a multimeter. At 70°F, the sensor should read approximately 11.8k ohms; significant deviations or an open circuit indicate the harness needs replacement.

Will this work with aftermarket defrost boards?
While designed for Lennox OEM control boards, it is compatible with any board programmed for 10k ohm NTC thermistor inputs, provided the lead length and connector pins match the application requirements.

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.