Which sensor is NOT an NTC thermistor?

The sunload sensor is not an NTC (Negative Temperature Coefficient) thermistor because its primary function revolves around measuring the intensity of sunlight rather than temperature changes. While NTC thermistors are designed to decrease resistance with an increase in temperature and are commonly used in various automotive temperature sensing applications, the sunload sensor operates differently.

Sunload sensors typically utilize phototransistors or similar light-sensitive components to detect solar radiation and are often employed in climate control systems to adjust HVAC settings based on the amount of sunlight entering the vehicle. This is a distinct role that does not involve measuring temperature directly.

In contrast, the other sensors listed—such as the in-vehicle sensor, ambient sensor, and engine coolant temperature sensor—are integral parts of the vehicle's temperature management systems and utilize NTC thermistors to provide accurate temperature readings that affect performance and comfort. These sensors respond to changes in temperature by varying their resistance, which is a key principle of NTC thermistors.