Theory Of Operation

The HVAC Module uses a variety of sensors to adjust HVAC operation to obtain optimal performance. These sensors are continuously monitored by the HVAC Module to assure that they are in range. An active 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 Evaporator Temperature Sensor monitors the surface temperature of the HVAC Evaporator and supplies an input signal to the HVAC Module. The input signal value is used to optimize the HVAC system performance and to protect the HVAC Evaporator from freezing. The Evaporator Temperature Sensor resistance value will change in response to the surface temperature of HVAC Evaporator. The resistance value is electronically transferred to the HVAC Module using Evaporator Sensor Signal circuit. Normal operation of the sensor the resistive value decreases when the HVAC evaporator temperature decreases and the sensor resistive value increases when the HVAC evaporator temperature increases.