Temperature Sensors

OUTSIDE TEMPERATURE SENSOR

Outside Temperature Sensor (Typical):

Right And Left Solar Sensors (Typical):

This sensor is located in front of the radiator. The sensor data is processed by the HVAC Programmer and displayed on the HVAC control assembly.
During periods of city traffic and idle conditions, engine heat can surround the area of the outside temperature sensor and cause temperature readings that are higher than the actual outside air temperature. To help eliminate these "false" readings, programming techniques are used to minimize unwanted temperature variations.
A temperature "memory" feature is used in the programmer outside temperature programming to help provide greater accuracy under engine restart conditions. If engine coolant temperature is less than 10°C (18°F) above the outside temperature sensor reading, the actual sensed outside temperature is displayed. However, if engine coolant is greater than 10°C (18°F) above the sensor reading, "memorized" outside temperature is displayed. This is the displayed temperature sensed when the engine was previously operating. At car speeds greater than 20 mph, the outside temperature display may be allowed to increase, but only after a built-in 80 second time delay which allows for outside air to cool the sensor. The 80 second time delay starts when vehicle speed reaches or maintains at least 20 mph. If the sensor reading is ever less than the displayed value or if the vehicle speed is 45 mph or greater, there is no delay and outside temperature changes are displayed as rapidly as possible.
The outside temperature display can be updated by pressing "AUTO", "A/C" ("VENT" on Buick), and "RECIRC" buttons simultaneously.

INSIDE TEMPERATURE SENSOR
The inside temperature sensor is a temperature sensitive resistor like the outside temperature sensor; as inside air temperature increases, resistance decreases and as inside air temperature decreases, resistance increases.
A hose connected to the inside air temperature sensor continually draws passenger compartment air over the sensor, increasing the accuracy of the temperature reading.
The HVAC programmer monitors the inside temperature signal and uses this information to help determine command signals.

SOLAR SENSORS
The solar sensors are light sensitive photo-diodes which monitor the heat load of the sun on the vehicle. There are two solar sensors utilized by the dual zone (CJ2) A/C system, one right and one left. The sensors are located on top of the instrument panel, one on each side, mounted under the defroster grill where sunlight can reach them. The Pontiac system (C68) uses only one solar sensor.
The HVAC programmer compares the solar sensor readings to the inside temperature reading and then determines how much cooling is required to reach and maintain the desired SET temperature on each side of the vehicle.
Operation of the solar sensor will be effected it is covered. To ensure proper operation, make sure that there is no obstruction of sunlight to the sensor.