Lennox Air Conditioner Sensor & Thermistor Parts

OEM Lennox Air Conditioner Thermistor and Sensor Parts

Lennox thermistors are precision temperature sensors that tell your system how cold the air is and when to cycle the compressor on and off. A faulty thermistor sends wrong signals, causing the system to behave erratically—no cooling, excessive cycling, or refusing to start at all. OEM Lennox thermistors are calibrated to exact tolerances and match your model's control board programming perfectly.

Thermistor problems are often blamed on the thermostat or control board, but the sensor itself is the weak link. Since they're exposed to moisture and temperature swings, they fail quietly with age. A simple $30 part replacement can restore reliable temperature control and prevent unnecessary service calls.

• System won't cool past a certain temperature: Thermistor reading incorrectly high
• Compressor cycles on and off constantly: Sensor sending false temperature signals
• Indoor unit icing up: Thermistor not detecting cold evaporator coil
• No cooling whatsoever: Broken thermistor preventing compressor start signal
• Thermostat display doesn't match actual room temp: Sensor wire disconnected or corroded

Locate your Lennox model and find the exact thermistor or sensor your system needs. Browse our Lennox air conditioner sensor thermistor parts by model number for precision replacements.

Lennox Air Conditioner Sensor & Thermistor Parts: Questions & Troubleshooting

What does a thermistor do in my Lennox air conditioner?

A thermistor is a temperature sensor that measures air temperature on the indoor coil and reports it to the control board. Based on that reading, the board decides whether to run the compressor, cycle the fan, or shut down. If the thermistor fails or reads incorrectly, the system loses feedback and can't control cooling properly. It's a simple part with a huge job.

Why did my Lennox thermistor fail?

Thermistors fail from age, moisture exposure, or corrosion of the sensor wire connections. Window and portable units are especially vulnerable because they're exposed to humidity. Loose connections from vibration can also break the sensor circuit. Most failures are gradual—erratic readings before complete failure—so temperature control gets unreliable before the system stops cooling entirely.

How do I find the thermistor in my Lennox unit and confirm it's the problem?

Indoor units: open the blower compartment and look for a thin wire probe touching the indoor coil fins. Outdoor units may have a sensor wire running from the control board to the coil. Check for loose connections, corrosion, or physical damage. If the sensor wire is disconnected or corroded green, that's your culprit. Replace it and cooling should return to normal.

Is a Lennox thermistor the same as a thermostat?

No—they're completely different. Your thermostat is what you control from the wall; it sends a demand signal for cooling. The thermistor is an internal sensor that gives the control board real-time feedback about temperature. A bad thermostat is usually a control issue; a bad thermistor causes the system to misread conditions and behave incorrectly.

Convenient Online Ordering for Lennox A/C Sensor & Thermistor Parts

Ensure your Lennox air conditioner operates at peak efficiency with genuine sensor and thermistor parts. Easily find and order the exact replacements you need by using our model or part number lookup. Our parts ship the same day, so you can get your A/C unit back up and running quickly. Whether you're a homeowner tackling a DIY repair or a professional technician, our extensive inventory and resources make it easy to find the right parts online. For more detailed repair guides and troubleshooting tips, visit our Air Conditioner Repair Help section. If you need additional air conditioner parts, browse our selection of Lennox Air Conditioner Parts to keep your system running smoothly.

Lennox Air Conditioner Model Number: Where to Look

On Lennox air conditioners, look for the model number on the exterior nameplate of the condenser, usually on the side of the cabinet or near the control panel. If it is not visible there, check inside the access panel, but turn off power before opening the cabinet. The model number identifies the complete unit, not just a sensor or another individual part. Type it into our model number lookup and the catalog narrows to parts made for your unit, including sensors, thermistors, and other associated parts. Matching the whole model first helps you avoid confusing similar Lennox systems and gives you a faster, more accurate path to the parts you need.