Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step ensures that the primary HVAC system is functioning properly.
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The DTCs listed could set if a calibration of the actuators is performed.
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If the condition does not occur when a A/C request has been made then you must bypass the A/C compressor and cooling system diagnostic information.
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This step ensures that the front auxiliary control assembly is providing an auxiliary air temperature input to the auxiliary HVAC control module.
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This step ensures that the rear seat audio control is providing an auxiliary air temperature input to the auxiliary HVAC control module.
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When taking a temperature reading allow for a 3°C (5°F) temperature variance.
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When the front auxiliary HVAC control assembly is disconnected, and there is no fault on auxiliary air temperature switch control circuit, the scan tool will read a high count value for the Air Temp. Switch Pos. parameter. A short to ground on circuit will have low count value.
Step | Action | Values | Yes | No | ||||||||
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Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: Auxiliary air temperature can not be adjusted from one or both auxiliary controls or auxiliary cooling is insufficient. | ||||||||||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | |||||||||
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Important:: The auxiliary HVAC control assembly operates independently of the HVAC control module to provide cooled airflow through the auxiliary system. Does the HVAC control module operate and provide sufficient cooling? | -- | Go to Step 3 | Go to Too Cold in Vehicle | |||||||||
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Important:: If during this diagnostic procedure the auxiliary HVAC control module is disconnected a recalibration of actuators must be performed to avoid misdiagnosis.
Does the scan tool display DTC B0434 or B3764? | -- | Go to Step 4 | ||||||||||
4 |
Does the auxiliary blower motor operate at all? | -- | Go to Step 5 | |||||||||
5 | Does the auxiliary blower motor operate at the desired speed for each speed position? | -- | Go to Step 6 | |||||||||
Does the Auxiliary Too Hot in Vehicle concern occur when A/C is required? | -- | Go to Step 7 | Go to Step 9 | |||||||||
7 |
Important: The ambient air temperature must be above 5°C (40°F) for A/C compressor operation.
Does the A/C compressor operate? | -- | Go to Step 8 | |||||||||
8 | Perform the refrigerant system performance test. Refer to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 9 | ||||||||
Does the Air Temp. Switch Pos. parameter change from a low count to high count? | -- | Go to Step 10 | Go to Step 13 | |||||||||
Does the Rear Temp. Select Sw. parameter change with each air temperature button press? | -- | Go to Step 11 | Go to Step 24 | |||||||||
11 |
Does the paper stay in place? | -- | Go to Step 12 | Go to Step 16 | ||||||||
Does the resistance measure near the sensor resistance table value? | -- | Go to Step 23 | Go to Step 25 | |||||||||
13 |
Does the voltage measure near specified value? | 5 V | Go to Step 14 | Go to Step 18 | ||||||||
14 | Measure the voltage of the 5-volt reference circuit to the low reference circuit of the front auxiliary HVAC control assembly. Does the voltage measure near specified value? | 5 V | Go to Step 15 | Go to Step 20 | ||||||||
Do the counts read below specified value? | 5 Counts | Go to Step 26 | Go to Step 19 | |||||||||
16 |
Does the voltage measure near specified value? | 12 V | Go to Step 17 | Go to Step 21 | ||||||||
17 |
Does the voltage measure near specified value? | 12 V | Go to Step 25 | Go to Step 22 | ||||||||
18 | Test the 5-volt reference circuit of the front auxiliary HVAC control assembly for the following conditions:
Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 27 | ||||||||
19 | Test the auxiliary front air temperature switch signal circuit of the front auxiliary HVAC control assembly for the following conditions:
Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 27 | ||||||||
20 | Test the low reference circuit of the front auxiliary HVAC control assembly for the following conditions:
Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 27 | ||||||||
21 | Test the auxiliary inside air temperature sensor assembly control circuit of the auxiliary inside air temperature sensor assembly for the following conditions:
Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 27 | ||||||||
22 | Repair the ground circuit of the auxiliary inside air temperature sensor assembly. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | -- | ||||||||
23 | Check the suspect air temperature sensor for proper installation. Refer to Air Temperature Sensor Replacement - Upper Auxiliary or Air Temperature Sensor Replacement - Lower Auxiliary . Did you find and correct the condition? | -- | Go to Step 32 | Go to Heating Performance Diagnostic in Heating, Ventilation and Air Conditioning | ||||||||
24 | Inspect for poor connections at the harness connector of the rear seat audio control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 28 | ||||||||
25 | Inspect for poor connections at the harness connector of the suspect air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 29 | ||||||||
26 | Inspect for poor connections at the harness connector of the front auxiliary HVAC control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 30 | ||||||||
27 | Inspect for poor connections at the harness connector of the auxiliary HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 31 | ||||||||
28 | Replace the rear seat audio control module. Refer to Rear Seat Audio Control Replacement in Entertainment. Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||||
29 | Replace the suspect air temperature sensor. Refer to one of the following procedures: Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||||
30 | Replace the front auxiliary HVAC control assembly. Refer to Auxiliary Heater and Air Conditioning Control Replacement - Front . Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||||
31 | Replace the auxiliary HVAC control module. Refer to Auxiliary Heater and Air Conditioning Control Module Replacement . Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||||
32 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 | ||||||||
