*HVAC SYSTEM TEST (ATC)

For a complete wiring diagram Refer to Section 8W.

Theory of Operation


The HVAC System Test provides a starting point in the diagnostic process by identifying the appropriate diagnostic procedure or system test to perform when diagnosing a given symptom, condition, or DTC. It also provides a means for testing the entire HVAC system by utilizing the A/C Heater Control's On-Board System Tests. The On-Board System Tests can also assist in diagnosing stored DTCs. (Refer to 24 - HEATING & AIR CONDITIONING - DIAGNOSIS AND TESTING) for additional information about on-board diagnostics.



Diagnostic Test

1.HVAC SYSTEM TEST

NOTE: Diagnose and repair all active DTCs before diagnosing and repairing stored DTCs.



Make a selection based on the symptom, condition, or DTC that you want to diagnose.

For Any Active DTC
  • Refer to the Table of Contents in this Section for a complete list of all HVAC related symptoms.


Scan Tool Indicates HVAC Not Active On Bus


Complete HVAC System Test
  • Go To 2


A/C System Performance Test
  • Go To 2


General System Operation & Function Test
  • Go To 3


Actuator Calibration Test
  • Go To 4


Front Blower Motor Inoperative
  • Refer to *Front Blower Motor Inoperative (ATC) in this Section for the diagnostic test procedure.


Rear Blower Motor Inoperative
  • Refer to *Rear Blower Motor Inoperative in this Section for the diagnostic test procedure.


Rear Blend Door Inoperative
  • Refer to *Rear HVAC Blend Door Inoperable in this Section for the diagnostic test procedure.


Rear Mode Door Inoperative
  • Refer to *Rear HVAC Mode Door Inoperable in this Section for the diagnostic test procedure.

2.A/C SYSTEM PERFORMANCE TEST

NOTE: The following are prerequisites of the Cooldown Test. Verify each of the following before running the test:

  • If active, diagnose and repair DTC B1031 or B1032 before proceeding. Refer to the Table of Contents in this Section for a complete list of HVAC related symptoms.
  • Verify that the refrigerant system has an adequate charge. Check and repair as necessary before proceeding. (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - DIAGNOSIS AND TESTING - REFRIGERANT SYSTEM LEAKS).
  • Verify that the blower motor operates correctly in all speeds. Diagnose and repair all blower related faults before proceeding.
  • Verify that the work area ambient temperature is above 18.3°C (65°F) before proceeding. Move the vehicle to a warmer work area if necessary.
  • Verify that the evaporator temperature is above 18.3°C (65°F) before proceeding.
  • Verify that the A/C compressor is not running. If the A/C compressor is running, turn the A/C off and allow the evaporator to warm up before proceeding.





NOTE: The Cooldown Test can take up to two minutes to run. While the test is running, the A/C status indicator will flash. If the test passes, the A/C status indicator will stop flashing. However, if the test fails, both the A/C and EBL status indicators will flash alternately and an active DTC B10B2 will set. The status indicators will continue to flash until either a successful Cooldown Test is executed or until the vehicle is driven a specified number of miles or after 5 ignition cycles. In addition, DTC B10B2 will remain active until a successful Cooldown Test is executed. The test will stop running if any of the following occurs:

  • The ignition is turned off.
  • The A/C compressor is requested off.
  • DTC B1031 or B1032 sets during the test.





Does the scan tool display any DTCs?

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

3.GENERAL SYSTEM OPERATION & FUNCTION TEST

NOTE: If at anytime a DTC becomes active during this test, proceed to the conclusion question.

NOTE: If multiple DTCs become active, diagnose those that relate to a short circuit first.














Does the scan tool display any active DTCs?

Yes
  • Diagnose and repair the DTC(s). Refer to the Table of Contents in this Section for a complete list of HVAC related symptoms.


No
  • If you are here due to a stored DTC, it is possible that a technician may not have erased the DTC following a repair. If possible, verify if the vehicle was recently in for this type of service. Otherwise, either Go To 4 or visually inspect the related wiring harness for chafed, pierced, pinched, and partially broken wires and the wiring harness connectors for broken, bent, pushed out, and corroded terminals, and repair as necessary.
  • Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

4.ACTUATOR CALIBRATION TEST




Does the scan tool display any DTCs?

Yes
  • Diagnose and repair the DTC(s). Refer to the Table of Contents in this Section for a complete list of all HVAC related symptoms.


No
  • No problem found. However, if you are here due to a stored DTC, it is possible that a technician may not have erased the DTC following a repair. If possible, verify if the vehicle was recently in for this type of service. Otherwise, visually inspect the related wiring harness for chafed, pierced, pinched, and partially broken wires and the wiring harness connectors for broken, bent, pushed out, and corroded terminals, and repair as necessary.
  • Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).