HVAC System Test (ATC)

HVAC SYSTEM TEST (ATC)

DIAGNOSTIC TEST

1. HVAC SYSTEM TEST

NOTE:
- The HVAC System Test consists of three tests. Test 2 tests A/C system performance, Test 3 tests for mode switch and door actuator circuit faults, Test 4 tests for door actuator calibration faults. Either perform all three tests for a complete system test or perform an individual test if diagnosing a specific symptom.
- Active DTCs must be resolved before diagnosing stored DTCs.

Turn the ignition on.
With the scan tool, erase HVAC DTCs.

Choose a diagnostic test to perform.

Complete HVAC System Test
Go To 2
A/C System Performance Test
Go To 2
Mode Switch & Door Actuator CKT Test
Go To 3
Actuator Calibration Test
Go To 4

2. A/C SYSTEM PERFORMANCE TEST

NOTE: The following are prerequisites of the Cooldown Test. Verify each of the following before running the test:
- The test will not start if DTC B1031, B1032, B1040, B1044, B1045, B1058, B105C, B105D, B1099, B109A, B10A2, B10A6, B10A7, B10A8, B10A9, B10AD, B10AE, B10AF, B222A, or U0141 is active. If active, diagnose and repair the DTCs before proceeding. Refer to HVAC related symptoms.
- The Cooldown test will not start if the refrigerant pressure is not within specifications. Check and repair as necessary before proceeding.
- 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 16° C (60° 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 compressor is running, turn the A/C off and allow the evaporator to warm up before proceeding.

Once all of the prerequisites have been met, actuate the Cooldown Test by performing the following:
Start the engine.
With the scan tool in HVAC, select System Tests and then select Cooldown test.

NOTE:
- The Cooldown Test can take up to two minutes to run. The test will stop running if any of the following occurs:
- The ignition is turned off.
- The compressor is requested off.
- The blower control is moved to the off position, unless the control was in the off position when the test was started. In this case, moving the blower control out of the off position and then returning it to the off position will stop the test
- DTC B1031 or B1032 sets during the test.
- the control receives a bus message to stop the test.

- Running the test will cause the EBL status indicator to flash. If the test passes, the EBL status indicator will stop flashing. If the test fails, both the EBL and A/C status indicators will flash alternately.

Allow the test to run to completion before proceeding.
With the scan tool, select View DTCs.

Q: Does the scan tool display any DTCs?

YES: Diagnose and Repair the DTC(s). Refer to HVAC related symptoms. Rerun the Cooldown Test after the repair is complete.
NO: As necessary, either Go To 3 or 4, or Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

3. MODE SWITCH & DOOR ACTUATOR CIRCUIT TEST

NOTE:
- If at anytime a DTC becomes active during this test, proceed to the conclusion question.
- If multiple DTCs become active, diagnose those that relate to a short circuit first.

If not do so previously, start the engine.
Turn the blower control to manual low.
Turn the Left and Right Blend controls to full cold.
Turn the Mode control to panel.
Monitor the scan tool for active HVAC DTCs while performing the following test steps.
Press the A/C mode switch on, wait 30 seconds, press it off, and then proceed to the next step.
Press the Rear Defrost mode switch on, wait 30 seconds, press it off, and then proceed to the next step.
Press the Recirculation mode switch on,wait 30 seconds, press it off, and then proceed to the next step.
Turn the Left Blend control to full hot, wait 30 seconds, turn it to full cold, and then proceed to the next step.
Turn the Right Blend control to full hot, wait 30 seconds, turn it to full cold, and then proceed to the next step.
Turn the Mode control to every door position. Leave it in each position for 30 seconds.

Q: Does the scan tool display any active DTCs?

YES: Diagnose and repair the DTC(s). Refer to HVAC related symptoms.
NO: As necessary, either Go To 4 or Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

4. ACTUATOR CALIBRATION TEST
With the scan tool, select System Tests and then select Actuator Calibration Test. When the test is complete, select View DTCs.

Q: Does the scan tool display any DTCs?

YES: Diagnose and repair the DTC(s). Refer to HVAC related symptoms.
NO: No problem found. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test