Lennox 26G10 Defrost Sensor

The Lennox 26G10 Defrost Sensor is a critical thermistor-based control designed for precision management of the defrost cycle in residential Lennox heat pump units. Engineered to monitor the outdoor evaporator coil temperature, this sensor triggers the defrost sequence to prevent excessive ice buildup that can choke airflow and degrade system efficiency. This specific model features an L70-35F temperature rating, meaning it is calibrated to open at 70°F and close at 35°F. For field technicians, it is important to note that the 26G10 is identical to 26G1001, offering a direct 1:1 replacement for vintage or modern boards that utilize this specific switching logic. Operating within a functional range of -76°F to 302°F, this OEM Lennox part ensures that the control board receives accurate resistance data to initiate the reversing valve and auxiliary heat strips exactly when needed. Replacing a drifted or failed sensor restores the heat pump’s COP (Coefficient of Performance) and prevents unnecessary mechanical strain on the compressor during cold-weather operation.

• Precise L70-35F Calibration: Ensures the defrost cycle initiates and terminates at the exact thermal setpoints required by the control logic.
• OEM Compatibility: Guaranteed fit for Lennox systems requiring part numbers 26G10 or 26G1001 without needing lead splicing or custom brackets.
• Wide Temp Tolerance: Constructed to withstand extreme coil temperatures ranging from -76°F up to 302°F without degradation.
• System Efficiency: Prevents "nuisance defrosting" and "coil icing," maintaining optimal heat transfer across the outdoor fins.

How do I test a Lennox 26G10 defrost sensor in the field?
Disconnect the sensor and measure the resistance (Ohms) across the leads. Compare your reading to the Lennox thermistor temperature-resistance chart; if the sensor is "open" or "shorted" while within its normal operating range, it requires replacement.

What are the signs of a failing 26G10 sensor?
Common indicators include heavy ice accumulation on the outdoor coil, the unit staying in defrost mode for more than 15 minutes, or the outdoor fan failing to cycle off during the defrost sequence.

Is the 26G10 interchangeable with the 26G1001?
Yes, these parts are technically identical in specification, fitment, and thermal response, making them interchangeable for all Lennox HVAC applications.

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.