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HVAC System Test






HVAC SYSTEM TEST

For a complete wiring diagram Refer to the Wiring Information.

1. HVAC SYSTEM TEST

NOTE: The HVAC System Test consists of four tests. Test 2 tests A/C system performance, Test 3 tests for mode switch, door actuator circuit, and auxiliary coolant pump circuit faults, Test 4 tests for shorted door actuator circuits, and Test 5 tests for door actuator calibration faults. Either perform all four tests for a complete system test or perform an individual test if diagnosing a specific symptom.

NOTE: Active DTCs must be resolved before diagnosing stored DTCs.

1. Start the engine.
2. 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, AND Auxiliary Coolant Pump Ckt Test

- Go To 3

Actuator DTC Detection Test

- Go To 4

Actuator Calibration Test

- Go To 5

2. A/C SYSTEM PERFORMANCE TEST

NOTE: The work area ambient temperature must be above 15.6°C (60°F) and the evaporator temperature must be above 18.3°C (65°F) in order to test A/C system performance.

NOTE: Before actuating the Cool down Test, verify that the mode setting is not in a defrost position and 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 with the test.

NOTE: Running the Cool down test will cause the A/C status indicator to flash.

NOTE: One or more status messages will display on the scan tool after running the Cool down Test. These messages will clear after paging back out of this test function. Therefore, it is important to note all messages before doing so.

1. Set the mode to the Panel position.
2. Verify that the front blower motor operates correctly in all speeds. Diagnose and repair all blower related faults before proceeding with this test.
3. Set the front blower speed to high.
4. With the scan tool in HVAC, select System Tests and then select Cool down test. Allow the test to run to completion.

Does the scan tool display a status message that indicates a fault has occurred?

Yes, Conditions Too Cold - Test Not Run

- If running, turn the A/C compressor off. Verify that the work area ambient temperature is above 15.6°C (60°F). If not, move the vehicle to a warmer work area. Verify that the evaporator temperature is above 18.3°C (65°F). If not, set the front blower to high speed and allow the blower to run for five minutes. Then, rerun the Cool down Test.

Yes, Blowers Not On High - Test Not Run

- Set the front blower speed to high speed and then rerun the Cool down Test.

Yes, No Results Stored/Test Not Complete

- Verify that power is not interrupted while rerunning the Cool down Test.

No

- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test.

3. MODE SWITCH, DOOR ACTUATOR CIRCUIT, AND AUXILIARY COOLANT PUMP CIRCUIT 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.

1. Set the front blower speed to low.
2. Set the Blend control to full cold.
3. Set the Mode control to Bi-Level/Recirc.
4. If equipped, set the Rear Fan switch on the Rear A/C Heater Control to off.
5. If equipped, set the Rear Blend switch on the Rear A/C Heater Control to full cold.
6. Monitor the scan tool for active HVAC DTCs while performing the following test steps.
7. Press the A/C mode switch on, wait 30 seconds, press it off, and then proceed to the next step.
8. Press the Rear Defrost mode switch on, wait 30 seconds, press it off, and then proceed to the next step.
9. Press and hold the Rear Washer mode switch for several seconds, release it, and then proceed to the next step.
10. Set the Blend control to full hot, wait 30 seconds and then set it to full cold.
11. Turn the Mode control to every door position. Leave it in each position for 30 seconds.
12. If equipped, set the Rear Blower control to Rear Control.
13. If equipped, set the Rear Fan switch on the Rear A/C Heater Control to high speed.
14. If equipped, slowly turn the Rear Blend switch on the Rear A/C Heater Control to full hot, wait 30 seconds and then turn it back to full cold.
15. If equipped, turn the Rear Fan switch on the Rear A/C Heater Control to off.
16. If equipped with rear HVAC, with the scan tool, select the following: Actuators, Auxiliary Coolant Pump, Start, and Constant On. Allow the pump to run for approximately one minute.

Does the scan tool display any active DTCs?

Yes

- Diagnose and repair the DTC(s).

No

- As necessary, either Go To 4 or 5 , or Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

4. ACTUATOR DTC DETECTION TEST
1. With the scan tool, select System Tests and then select Actuator DTC Detection. When the test is complete, select View DTCs.

Does the scan tool display any DTCs?

Yes

- Diagnose and repair the DTC(s). If multiple DTCs are present, beginning with the common circuits, diagnose and repair all short high DTCs and then all short low DTCs.

No

- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test.

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

Does the scan tool display any DTCs?

Yes

- Diagnose and repair the DTC(s).

No

- No problem found.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test.

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