Sprinter 2500 V6-3.0L DSL Turbo VIN 45 (2007)
Evaporator Temperature Sensor / Switch: Description and Operation
Controls - Front
Description
DESCRIPTION
NOTE: Cutaway of typical HVAC housing shown for clarity.
The front evaporator temperature sensor (1) measures the temperature of the conditioned air downstream of the front A/C evaporator (3). The front
evaporator temperature sensor is an electrical thermistor mounted on the end of a molded plastic housing that is inserted into the side of the HVAC
housing near the coldest point of the front A/C evaporator. The front evaporator temperature sensor is retained in the HVAC housing by two integral
retaining tabs and is connected to the vehicle electrical system by use of a wire lead and connector with two terminals.
The external location of the front evaporator temperature sensor allows the sensor to be removed and installed without disturbing the refrigerant in the
front A/C system.
Operation
OPERATION
The front evaporator temperature sensor monitors the surface temperature of the front A/C evaporator and supplies an input signal to the A/C-heater
control. The A/C-heater control uses the front evaporator temperature sensor input signal to optimize front A/C system performance and to protect the
front A/C system from evaporator freezing. The front evaporator temperature sensor will change its internal resistance in response to the temperatures it
monitors and is connected to the A/C-heater control through sensor ground circuit and a 5-volt reference signal circuit. As the temperature of the front
A/C evaporator decreases, the internal resistance of the front evaporator temperature sensor decreases.
The A/C-heater control uses the monitored voltage reading as an indication of front evaporator temperature. The A/C-heater control is programmed to
respond to this input by requesting the powertrain control module (PCM) or the engine control module (ECM) (depending on engine application) to
adjust the front compressor swash plate angle as necessary to optimize A/C system performance and to protect the A/C system from evaporator freezing.
The front evaporator temperature sensor is diagnosed using a scan tool.
The front evaporator temperature sensor cannot be adjusted or repaired and must be replaced if inoperative or damaged.
