Grand Cherokee 2WD V6-3.7L (2008)
Evaporator Temperature Sensor / Switch: Description and Operation
Operation
OPERATION
The evaporator temperature sensor monitors the temperature of the conditioned air downstream of the A/C evaporator and supplies an input signal to the
A/C-heater control. The A/C-heater control uses the evaporator temperature sensor input signal to optimize A/C system performance and to protect the
A/C system from evaporator freezing. The 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 A/C evaporator
decreases, the internal resistance of the evaporator temperature sensor decreases.
The A/C-heater control uses the monitored voltage reading as an indication of 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 cycle the
A/C compressor clutch as necessary to optimize A/C system performance and to protect the A/C system from evaporator freezing.
The evaporator temperature sensor is diagnosed using a scan tool See: Heating and Air Conditioning/Testing and Inspection/Component Tests and
General Diagnostics/Heating-A/C System Diagnostics.
The evaporator temperature sensor cannot be adjusted or repaired and must be replaced if found inoperative or damaged.
