Theory Of Operation
The HVAC A/C Heater Control uses a variety of sensors to adjust HVAC operation to obtain optimal performance. These sensors are continuously monitored by the A/C Heater Control to assure that they are in range. An active Diagnostic Trouble Code (DTC) indicates that a sensor is out of range. A stored DTC indicates that the sensor was out of range but is currently within range.
The Floor Duct Temperature Sensor monitors the air temperature of the air from the floor duct and supplies an input signal to the A/C Heater Control. The Floor Duct Temperature Sensor resistance value will change in response to the air temperature from the Floor duct. The resistance value is electronically transferred to the A/C Heater Control using a sensor ground circuit and a 5-volt reference signal circuit. Normal operation of the sensor the resistive value decreases when the floor duct air temperature decreases and the sensor resistive value increases when floor duct temperature increases.