Temperature Sensor Input

Inside Air Temperature Sensor Description

The following air temperature sensors affect the automatic control of the in-vehicle temperature.

- An in-vehicle sensor
- An outside air sensor

Both of the sensors are temperature-sensitive thermistors. The resistance of the sensors varies inversely to the temperature. The resistance value determines level of the signal that is sent to the heater-A/C control. The heater-A/C control microprocessor uses this information in order to develop command signals for the following components:

- The vacuum solenoid module
- The temperature motor actuator
- The blower motor pulse width module

A hose duct connects the in-vehicle sensor housing to an aspirator. Air flow from the HVAC module creates a slight vacuum at the aspirator end of the hose. This vacuum completes the following functions:

- Draws in-vehicle air over the in-vehicle sensor
- Improves the accuracy of the cabin temperature that is measured by the sensor

Ambient Outside Air Temperature Sensor Description

The outside air temperature sensor is located in the front grill area under the front bumper of the vehicle. The HVAC control head uses this sensor to receive information on ambient air temperature. With this information, the HVAC control head will give the driver the outside air temperature on the digital display. If the outside temperature increases, the displayed temperature will not change until:

- The vehicle's speed is above 32 km/h (20 mph) for approximately one and a half minutes.
- The vehicles speed is above 72 km/h (45 mph) for approximately one minute.

These delays help prevent false readings. If the displayed temperature goes down, the outside temperature display is updated immediately. If the vehicle has been turned off for more than three hours, the current outside temperature will be shown when the vehicle is started. If it has been turned off for less than three hours, the temperature will be recalled from the previous vehicle operation.

Sun Load Sensor Description

The sun load temperature sensor is located on a removable grille in the center of the I/P upper trim pad. This sensor measures the amount of heat that is generated from the sun shining in the vehicle.