2012 Jeep Wrangler JK Factory Service Manual 24 - Heating and Air Conditioning

SENSOR, Temperature, In-Car

DESCRIPTION

DESCRIPTION

The in-car temperature sensor (1) is used in the Automatic Temperature Control (ATC) heating-A/C system only. The in-car temperature sensor consists of an aspirator motor (2) and a temperature thermistor (3). The in-car temperature sensor sends a resistance signal to the ATC A/C-heater control and is attached to the instrument panel, below the steering column.

OPERATION

OPERATION

Air is drawn from the passenger compartment by the aspirator motor and flows over the temperature thermistor. The thermistor changes resistance with air temperature. The Automatic Temperature Control (ATC) A/C-heater control receives the resistance signal and calculates the temperature of the air drawn into the in-car temperature sensor. The ATC system then makes adjustments to maintain the optimum passenger compartment comfort.

The in-car temperature sensor cannot be adjusted or repaired and must be replaced if inoperative or damaged.

DIAGNOSIS AND TESTING - IN-CAR TEMPERATURE SENSOR

DIAGNOSIS AND TESTING - IN-CAR TEMPERATURE SENSOR



NOTE:

For complete circuit diagrams, see Wiring Information. Wiring Information includes wiring diagrams, connector pin-out and location views, details of wire harness routing and retention, splice and ground locations and proper wire and connector repair procedures.

Using a scan tool, check for Diagnostic Trouble Codes (DTCs) related to the in-car temperature sensor and the A/C-heater control. If any DTCs are found, repair as necessary (Refer to 28 - DTC-Based Diagnostics/HVAC - Diagnosis and Testing) . If no DTCs are found, perform the two following tests. Replace the in-car temperature sensor if the sensor fails either test.


  1. Remove the in-car temperature sensor and place it on a workbench (Refer to 24 - Heating and Air Conditioning/Controls/SENSOR, Temperature - Removal) .

    2.  
  2. Note the current ambient air temperature of the work area.

    3.  
  3. Use an ohm meter and check the resistance between pins 1 and 2 of the in-car temperature sensor. Compare the temperature of the work area to the found resistance value. The resistance should be within specifications as listed in the Resistance and Temperature chart. If not OK, replace the in-car temperature sensor.

    4.  

RESISTANCE AND TEMPERATURE

Air Temperature Range

Low Resistance Range (kohm)

High Resistance Range (kohm)

-21° to -15°C (-5° to 5°F)

292 ± 1.0

223 ± 0.9

-14° to -9°C (6° to 15°F)

198 ± 0.9

161 ± 0.8

-8° to -4°C (16° to 25°F)

144 ± 0.8

123 ± 0.8

-3° to 1°C (26° to 35°F)

111 ± 0.7

95 ± 0.7

2 to 7°C (36° to 45°F)

86 ± 0.7

70 ± 0.6

8 to 12°C (46° to 55°F)

64 ± 0.6

55 ± 0.5

13° to 18°C (56° to 65°F)

51 ± 0.5

42 ± 0.4

19° to 23°C (66° to 75°F)

39 ± 0.4

33 ± 0.3

24° to 29°C (76° to 85°F)

31 ± 0.3

26 ± 0.3

30° to 35°C (86° to 95°F)

24 ± 0.3

20 ± 0.3

36° to 40°C (96° to 105°F)

18 ± 0.3

16 ± 0.3

41° to 46°C (106° to 115°F)

15 ± 0.3

13 ± 0.3


ASPIRATOR MOTOR TEST

The in-car temperature sensor uses an aspirator motor to draw air from the passenger compartment and flow it over the temperature thermistor. Test the motor as follows.


  1. Turn the ignition switch to Run position.

    2.  
  2. Place a small piece of newspaper in front of the aspirator motor opening grille (1), located on the steering column opening cover (2). If the paper sticks to the grille, the aspirator motor is operating properly. The piece of paper should be only large enough to cover the opening.

    3.  
  3. If the paper does not stick to the grille, check the in-car temperature sensor electrical connections and wiring. If connections and wiring are OK, replace the in-car temperature sensor.

    4.  

TEMPERATURE THERMISTOR TEST

The in-car temperature sensor uses a temperature thermistor to provide resistance values that correlate with temperature change. Test the thermistor as follows.

REMOVAL

REMOVAL

WARNING:

Disable the airbag system before attempting any steering wheel, steering column or instrument panel component diagnosis or service. Disconnect and isolate the negative battery (ground) cable, then wait two minutes for the airbag system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to follow these instructions may result in accidental airbag deployment and possible serious or fatal injury.



NOTE:

LHD model shown. RHD model similar.


  1. Disconnect and isolate the negative battery cable.

    2.  
  2. Remove the steering column opening cover (Refer to 23 - Body/Instrument Panel/COVER, Steering Column Opening - Removal) .

    3.  
  3. Disconnect the wire harness connector (1) from the in-car temperature sensor (2).

    4.  
  4. Remove the two screws (3 and 4) that secure the in-car temperature sensor to the instrument panel (5) and remove the sensor.

    5.  

INSTALLATION

INSTALLATION



NOTE:

LHD model shown. RHD model similar.


  1. Position the in-car temperature sensor (2) to the instrument panel (5).

    2.  
  2. Install the two screws (3 and 4) that secure the in-car temperature sensor to the instrument panel. Tighten the screws securely.

    3.  
  3. Connect the wire harness connector (1) to the in-car temperature sensor.

    4.  
  4. Install the steering column opening cover (Refer to 23 - Body/Instrument Panel/COVER, Steering Column Opening - Installation) .

    5.  
  5. Reconnect the negative battery cable.

    6.