Faulty Thermistor Symptoms

Thermistors serve a variety of purposes and can be found in everything from refrigerators and hair dryers to vehicles. Typically, they’re used as temperature sensors but can be extremely useful when it comes to current protection. So, what happens when a thermistor starts displaying incorrect readings? Learn more about faulty thermistor symptoms with Gateway Cable Company!

How Do I Know if a Thermistor is Bad?

For the most part, it’s easy to tell when you need to replace a thermistor. When a thermistor is failing, it’ll display incorrect temperatures, or you’ll see impossible temperature fluctuations. For example, you may initially get a reading of 210 degrees only to see the temperature drop to 189 degrees and jump back up again. Although other issues could be at play, if this happens frequently, the thermistor is likely failing.

Thermistors in car AC systems operate much like the smaller ones found in electronics — just on a larger scale. They measure temperatures and send resistance signals to the AC control module, allowing the system to automatically adjust so the cabin remains at the temperature you set. Faulty thermistor symptoms for vehicles are a little different. When a thermistor in a car is failing, the AC system will blow cold air for a short time or the blower will stop functioning correctly.

If you suspect thermistor failure, review our “how to test a thermistor” guide for more information!

What Causes Thermistor Failure?

Usually, thermistor failure is caused by an open circuit due to mechanical separation between the resistor element and lead material. This can happen as a result of improper handling, thermal mismatch, or heat damage. Another common reason thermistors fail is simply aging. Over time, the thermistor circuit becomes less accurate and displays incorrect temperatures. In this case, it’s easiest to choose a replacement.

How to Choose a Replacement Thermistor

There are two main types of thermistors. The first is negative temperature coefficient (NTC) thermistors. NTC thermistors decrease resistance when temperatures increase. The second is positive temperature coefficient (PTC) thermistors, which increase their resistance when the temperature increases. If you need a replacement thermistor, ask yourself the following questions:

  • What’s the base resistance of the thermistor you’re replacing?
  • What base resistance does your application need?
  • How do resistance and temperature relate to this application? Should resistance decrease or increase as the temperature rises?
  • What’s the ideal thermistor size and style for your application?

Shop for Replacement Electrical Parts at Gateway Cable Company!

When you need military-grade thermistors, cable assemblies, plugs, and more, Gateway Cable Company is your trusted source. We’re ISO 9001:2015 certified and DFARS compliant, ensuring the highest level of reliability for our customers. Contact us to learn more about faulty thermistor symptoms and to request a quote on a replacement!