82–SENSOR TOO COLD TO START COOLDOWN TEST (MTC)





For a complete wiring diagram Refer to Section 8W.


  • When Monitored:

    When executing the Cooldown Test.

  • Set Condition:

    If the A/C Heater Control senses that the evaporator temperature is below 18.3°C (65°F) when executing the Cooldown Test.


Possible Causes
  
FAULTS PRESENT IN THE HVAC SYSTEM
  
EVAPORATOR TEMPERATURE BELOW 18.3°C (65°F) AT START OF COOLDOWN TEST
  
HIGH RESISTANCE ON (C121) SENSOR GROUND CIRCUIT
  
HIGH RESISTANCE ON (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT
  
EVAPORATOR TEMPERATURE SENSOR
  
A/C HEATER CONTROL
  

NOTE: This DTC will display as active if the ignition is not cycled after running the Cooldown Test. Otherwise, it will display as stored until cleared.



Diagnostic Test

1.CHECK FOR ACTIVE DTC 31, 32, 83, OR 84 IN THE A/C HEATER CONTROL


  • Turn the blower control on.
  • Press the A/C mode switch down, turn the blower control to off, wait until both LEDs illuminate (approximately 5 seconds) and then release the A/C mode switch.

NOTE: The A/C status indicator displays active DTCs when the EBL status indicator is not illuminated and stored DTCs when the EBL status indicator is illuminated.




Does the A/C status indicator display DTC 31, 32, 83, or 84?

Yes
  • Diagnose and repair the DTC(s). Refer to the Table of Contents in this section for a complete list of HVAC related symptoms. Run the Cooldown Test again after the repair is complete.


No
  • Go To 2

2.ERASE DTCs IN THE A/C HEATER CONTROL

  • Turn the blower control on.
  • Press the A/C mode switch down, turn the blower control to off, wait until both LEDs illuminate (approximately 5 seconds) and then release the A/C mode switch.
  • When the A/C status indicator begins displaying DTCs, set the Mode switch to the floor position, simultaneously press the A/C mode switch and the EBL mode switch down until both LEDs start flashing (approximately 5 seconds) and then release the mode switches. Stored DTCs will clear from memory in approximately two seconds.






  • Go To 3

3.VERIFY IF DTC 82 SET DUE TO EVAPORATOR TEMPERATURE BEING BELOW 18.3°C (65°F)

CAUTION: The work area ambient temperature and the evaporator temperature must be above 18.3°C (65°F) in order to test A/C system performance.







  • Press and hold the A/C mode switch down and then turn the blower motor control to high speed. Continue to hold the A/C mode switch down until the A/C status indicator begins flashing, Then, release the mode switch. While the test is running, the A/C status indicator will flash once per second. If the test passes, the A/C status indicator will stop flashing. If the test fails, the A/C and EBL status indicators will flash alternately. Allow the test to run to completion before proceeding.





  • Go To 4

4.CHECK FOR DTCS IN THE A/C HEATER CONTROL

  • Turn the blower control on.
  • Press the A/C mode switch down, turn the blower control to off, wait until both LEDs illuminate (approximately 5 seconds) and then release the A/C mode switch.

NOTE: The A/C status indicator displays active DTCs when the EBL status indicator is not illuminated and stored DTCs when the EBL status indicator is illuminated.




Does the A/C status indicator display DTC 82?

Yes, & No Other DTCs Present
  • Go To 5


Yes, & Other DTCs Present
  • Diagnose and repair the other DTC(s). Refer to the Table of Contents in this section for a complete list of HVAC related symptoms. Run the Cooldown Test again after the repair is complete.


No, But Other DTCs Present
  • Diagnose and repair the DTC(s). Refer to the Table of Contents in this section for a complete list of HVAC related symptoms. Run the Cooldown Test again after the repair is complete.


No, & No Other DTCs Present
  • Perform additional testing as necessary.

5.CHECK THE (C121) SENSOR GROUND CIRCUIT FOR HIGH RESISTANCE


NOTE: Ensure that the voltmeter leads are connected for positive polarity and that they meet the terminals in the connector. Also ensure that there is a good terminal to wire connection.






Is the voltage below 0.10 volts?

Yes
  • Go To 6


No

6.CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR HIGH RESISTANCE


NOTE: Ensure that the voltmeter leads are connected for positive polarity and that they meet the terminals in the connector. Also ensure that there is a good terminal to wire connection.






Is the voltage below 0.10 volts?

Yes


No