Thermistor Problems

A thermistor is a resistor device composed of semiconductors which have a resistance that varies as a function of temperature.

Undercooling

A dirty thermistor can can cause a vehicle's air-conditioning system to malfunction.A dirty thermistor can can cause a vehicle's air-conditioning system to malfunction.
Thermistors can develop problems that negatively impact their function.

Faulty thermistor readings in an air-conditioning system can lead to less or no cooled air being released, which can result from dirty wire connectors in the thermistor. In the case of a thermistor with dirty connections, “toggling” the thermistor, or physically shifting its position slightly, may temporarily relieve the problem. Applying a shot of electrical contact cleaner to the thermistor’s contacts typically offers a more permanent fix.

Overcooling

A faulty thermistor can generate a higher resistance level than needed and can communicate false temperature changes to a circuit board, which in turn can result in overcooling. A thermistor can be checked for faulty readings via an ohmmeter, which can be hooked up to the thermistor’s leads to check the resistance reading.

Errors

Thermistor errors can cause temperature-dependent devices, such as dryers, to malfunction not function at all. Thermistor errors can occur due to an electrical overload, which can burn out the contacts. Under such circumstances, replacing the thermistor can correct the issue.