Schematic Reference: HVAC Schematics

DEFINITION: The temperature cannot be adjusted, or the heating is insufficient.

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

When the heater or the defroster is ON, does the customer concern occur?

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Go to Step 6

Go to Step 9

1. Start the engine.
2. Turn OFF the HVAC controls.

Does the A/C compressor operate?

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Go to HVAC Compressor Clutch Does Not Disengage

Go to Step  7

Inspect the cooling system for the following:

1. A low coolant level.
2. A loose or worn accessory drive belt.
3. A leaking radiator hose or heater hose.
4. A kinked radiator hose or heater hose.
5. A missing radiator cap pressure seal.
6. A leaking radiator cap.

Did you find and correct the condition?

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Go to Step  24

Go to Step 8

Perform the Heating Performance Diagnostic. Refer to Heating Performance Diagnostic .

Did you find and correct the condition?

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Go to Step  24

Go to Step 9

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  24

Go to Step  10

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  11

Go to Step  15

1. Turn the engine OFF.
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 12

Go to Step  19

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  13

Go to Step  19

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  14

Go to Step 16

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  18

Inspect for a blocked or disconnected aspiration hose.

Did you find and correct the condition?

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Go to Step  24

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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  24

Go to Step  17

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  20

Go to Step  21

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  24

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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  24

Go to Step  22

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  24

Go to Step  23

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

Did you complete the replacement?

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Go to Step  24

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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  24

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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  24

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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