Ambient Temperature Sensor / Switch HVAC: Description and Operation

Sensor resistance chart:

Two temperature sensors are used in this system. One monitors vehicle interior temperature and the other monitors outside air or ambient temperature. Both are disc type thermistors which decrease resistance as they get hotter. Fig. 3 shows a chart of normal resistance of each sensor at various temperatures. These sensors and their associated resistance changes provide the input to the control system.

The in-car sensor is located behind the slots on instrument panel top cover. The ambient sensor is an integral part of the aspirator.