Schematic Reference: HVAC Schematics

Definition: The temperature cannot be adjusted, or the cooling is insufficient during A/C operation.

1

Did you perform the HVAC Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, perform the Recalibrate all Motors command in Instrument Panel Module Special Functions.
4. With a scan tool, observe the current DTC list in Instrument Panel Module.

Does the scan tool display any DTCs?

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Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

Place the blower motor switch in each speed position.

Does the blower motor operate in any of the speed positions?

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Go to Step 4

Go to Blower Motor Inoperative

Does the blower motor operate in the desired speed(s)?

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Go to Step 5

Go to Blower Motor Malfunction

Important:: Ambient air temperature must be above 5°C (41°F).

1. Cover the sunload sensor assembly.
2. Start the engine.
3. Fully open all panel outlets.
4. Place the temperature switch in the coldest position.
5. Place the mode switch in the panel (upper) position.
6. Place the blower motor switch in the maximum speed position.
7. Ensure that the vent (outside air) indicator is not illuminated.

Does the A/C compressor operate?

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Go to Step 6

Go to HVAC Compressor Clutch Does Not Engage

Perform the A/C system performance test.

Refer to Air Conditioning (A/C) System Performance Test .

Did you find and correct the condition?

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Go to Step  22

Go to Step  7

Inspect the air temperature sensors for proper installation. Refer to the following procedures:

Did you find and correct the condition?

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Go to Step  22

Go to Step 8

1. Start the engine.
2. Fully open all panel outlets.
3. Place the temperature switch in the 24°C (75°F) position.
4. Place the mode switch in the panel (upper) position.
5. Set blower speed to illuminate 2 bars on the fan speed indicator.
6. Place the right air temperature switch on the HVAC control module in the OFF position.
7. Inspect for airflow through the inside air temperature sensor by placing a 5-cm (2-in) square piece of paper over the sensor air inlet.

Does the paper stay in place?

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Go to Step  9

Go to Step  13

1. Turn OFF the ignition.
2. Install a scan tool.
3. Cover the sunload sensor assembly.
4. Start the engine.
5. Place the temperature switch in the 24°C (75°F) position.
6. Place the right air temperature switch on the HVAC control module in the OFF position.
7. With a scan tool, observe the Right and Left Solar Sensor data parameters in the Instrument Panel Module Open/Short Data list.

Does the scan tool indicate that the Right and Left Solar Sensor data parameters are greater than the specified value?

224 Counts

Go to Step  10

Go to Step  17

1. Uncover the sunload sensor assembly.
2. Direct a light source at the right and then the left side of the sunload sensor assembly.

Do the counts change similarly and correspond to the proper side of the sunload sensor assembly?

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Go to Step 11

Go to Step  17

1. Install a thermometer near the following air temperature sensors:

•

Inside

•	Upper right

•	Upper left

•	Lower right

•	Lower left

2. With a scan tool, observe the following data parameters in the Instrument Panel Module HVAC Sensor data list.

•	Inside Air Temp

•	Right AC Duct Temp

•	Left AC Duct Temp

•	Right Htr. Duct Temp

•	Left Htr Duct Temp

Does the scan tool indicate sensor temperatures near the thermometer temperatures within the specified range?

+3 to -3°C

(+5 to -5°F)

Go to Step  12

Go to Step  14

Does the customer need to change the set temperature frequently to maintain comfort?

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Go to Air Conditioning (A/C) System Does Not Maintain Set Temperature

Go to Step  16

Inspect for a blocked or disconnected aspiration hose.

Did you find and correct the condition?

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Go to Step  22

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Inspect for poor connections at the harness connector of the suspect temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step  22

Go to Step 15

Test the suspect temperature sensor resistance. Refer to Sensor Resistance Table .

Does the resistance measure near the Sensor Resistance Table value?

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Go to Step  18

Go to Step  19

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, adjust the Temperature Offset in Instrument Panel Module Special Function/Set Options as needed.

Did you complete the repair?

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Go to Step  22

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Inspect for poor connections at the harness connector of the sunload sensor assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step  22

Go to Step  20

Inspect for poor connections at the harness connector of the instrument panel integration module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step  22

Go to Step  21

Replace the suspect air temperature sensor. Refer to the following procedures:

Did you complete the replacement?

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Go to Step  22

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Replace the sunload sensor assembly. Refer to Sunload and Twilight Sentinel Sensor Replacement in Instrument Panel, Gauges, and Console.

Did you complete the replacement?

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Go to Step  22

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Important:: Perform the recalibration procedure for the instrument panel integration module.

Replace the instrument panel integration module. Refer to Instrument Panel Module Replacement in Body Control System.

Did you complete the replacement?

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Go to Step  22

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Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2