SENSOR-EVAPORATOR TEMPERATURE
DESCRIPTION
The evaporator temperature sensor measures the temperature of the conditioned air downstream of the A/C evaporator. The evaporator temperature sensor is an electrical thermistor (1) mounted on the end of a molded plastic housing (2) that is inserted into the driver side of the HVAC housing near the coldest point of the A/C evaporator. The evaporator temperature sensor is retained in the HVAC housing by two integral retaining tabs (3) and is connected to the vehicle electrical system by use of a wire lead and connector (4) with two terminals.
OPERATION
The evaporator temperature sensor monitors the surface temperature of 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 adjust the compressor swash plate angle as necessary to optimize A/C system performance and to protect the A/C system from evaporator freezing (refer to 24 - HEATING & AIR CONDITIONING/PLUMBING/COMPRESSOR-A/C - OPERATION for more information).
The evaporator temperature sensor is diagnosed using a scan tool (refer to 24 - HVAC Electrical Diagnostics for more information).
The evaporator temperature sensor cannot be adjusted or repaired and it must be replaced if found inoperative or damaged.
REMOVAL
NOTE: LHD model shown. RHD model similar.
1. Remove the HVAC housing assembly and place it on a workbench (refer to 24 - HEATING & AIR CONDITIONING/DISTRIBUTION /HOUSING-HVAC - HOUSING-HVAC ASSEMBLY - REMOVAL).
2. Remove the air distribution housing from the HVAC housing (refer to 24 - HEATING & AIR CONDITIONING/DISTRIBUTION/HOUSING-HVAC - HOUSING-AIR DISTRIBUTION - REMOVAL).
3. Using needle nose pliers (1), disengage the two retaining tabs (2) that secure the evaporator temperature sensor (3) to the driver side of the HVAC housing (4) and remove the sensor.
INSTALLATION
NOTE: LHD model shown. RHD model similar.
1. Install the evaporator temperature sensor (1) into the driver side of the HVAC housing (2) . Make sure the retaining tabs (3) are fully engaged to the housing.
2. Install the air distribution housing onto the HVAC housing (refer to 24 - HEATING & AIR CONDITIONING/DISTRIBUTION/HOUSING-HVAC - HOUSING-AIR DISTRIBUTION - INSTALLATION).
3. Install the HVAC housing assembly (refer to 24 - HEATING & AIR CONDITIONING/DISTRIBUTION/HOUSING-HVAC - HOUSING-HVAC ASSEMBLY - INSTALLATION).