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ATC







*HVAC SYSTEM TEST (ATC)

For a complete wiring diagram Consult Diagrams/Electrical.

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, door actuator circuit, auxiliary coolant pump circuit, and rear blower control circuit faults, Test 4 tests for shorted door actuator circuits and door actuator calibration faults. Either perform all three 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.

Start the engine.
With the scan tool, erase HVAC DTCs.
Press the ATC's POWER switch on.
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, Auxiliary Coolant Pump Ckt, & Rear Blower Control Ckt Test

- Go To 3

Actuator Calibration Test

- Go To 4

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 Cooldown Test, 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 with the test.

NOTE: Running the Cooldown 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 Cooldown Test. These messages will clear after paging back out of this test function. Therefore, it is important to note all messages before doing so.

Verify that the front blower motor operates correctly in all speeds. Diagnose and repair all blower related faults before proceeding with this test.
With the scan tool in HVAC, select System Tests and then select Cooldown 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 Cooldown Test.

Yes, No Results Stored/Test Not Complete

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

Yes, Refrigerant Temperature Sensor Error

- Refer to B1079-CLIMATE CONTROL COOL DOWN TEST EXCESSIVE TIME (ATC & MTC) for the diagnostic test procedure.B1079

Yes, DTC Set During Routine - Test Not Passed

- Refer to B1079-CLIMATE CONTROL COOL DOWN TEST EXCESSIVE TIME (ATC & MTC) for the diagnostic test procedure.B1079

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, AUXILIARY COOLANT PUMP CIRCUIT, & REAR BLOWER CONTROL 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.

Set the front blower speed to low.
Set the Rear Fan switch on the Rear A/C Heater Control to off.
Set the Rear Blend switch on the Rear A/C Heater Control to full cold.
Monitor the scan tool for active HVAC DTCs while performing the following test steps.
Press the AUTO mode switch, wait 30 seconds and then proceed to the next step.
Press the A/C mode switch on, wait 30 seconds, press it off, and then proceed to the next step.
Press the RECIRC mode switch on, wait 30 seconds, press it off, and then proceed to the next step.
Press the TEMP + mode switch until the temperature is set to the max heat setting, wait 30 seconds and then proceed to the next step.
Press the TEMP - mode switch until the temperature is set to the max cool setting, wait 30 seconds and then proceed to the next step.
Press the FLOOR mode switch, wait 30 seconds and then proceed to the next step.
Press the PANEL mode switch, wait 30 seconds and then proceed to the next step.
Press the BI-LEVEL mode switch, wait 30 seconds and then proceed to the next step.
Press the MIX mode switch, wait 30 seconds 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 FRONT DEFROST mode switch, wait 30 seconds and then proceed to the next step.
Press and hold the REAR WASHER mode switch for several seconds, release it, and then proceed to the next step.
Press the FAN - mode switch until the front blower speed is set to low, wait 30 seconds and then proceed to the next step.
Press the FAN + mode switch until the front blower speed is set to the high, wait 30 seconds and then proceed to the next step.
Press the FAN - mode switch until the front blower speed is set to low and then proceed to the next step.
Press the REAR FUNCTION mode switch. The rear-blower speed settings should display on the ATC display panel. Then, within 7 seconds, press the FAN + mode switch until the rear blower speed is set to high, wait 30 seconds and then proceed to the next step.
Press the REAR FUNCTION mode switch. The rear-blower speed settings should display on the ATC display panel. Then, within 7 seconds, press the FAN - mode switch until the rear blower speed is set to low, wait 30 seconds and then proceed to the next step.
Press the REAR FUNCTION mode switch. The words "CONTROL IN REAR" should display on the ATC display panel.
Slowly turn the Rear Fan switch on the Rear A/C Heater Control to high speed.
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.
Slowly turn the Rear Fan switch on the Rear A/C Heater Control to off.
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 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.
Does the scan tool display any DTCs?

Yes

- Diagnose and repair the DTC(s).

No

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

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