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

Important:: The RDO-BATT fuse must be removed for 20 seconds minimum. The HVAC control module requires 60 seconds to initialize after the HVAC fuse is reinstalled. Do not install a scan tool during this time.

1. Disconnect the scan tool.
2. Turn OFF the ignition.
3. Remove the RDO-BATT fuse to interrupt the keep alive memory of the HVAC control module.
4. Install the RDO-BATT fuse.
5. Install a scan tool.
6. Turn ON the ignition, with the engine OFF.
7. Observe the current DTC list in Heating, Ventilation and Air Conditioning using the scan tool.

Does the scan tool display DTC B0408, B0415 or B0416?

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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 each speed position?

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Go to Step  4

Go to Blower Motor Inoperative

Does the blower motor provide sufficient air flow?

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Go to Step  5

Go to Blower Motor Malfunction

1. Place the recirculation switch in the ON position.
2. Observe the recirculation door.
3. Place the outside air switch in the ON position.

Does the Recirculation Door move from the recirculation to the outside air position?

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Go to Step 6

Go to Air Delivery Improper

Does the Too Cold in Vehicle concern occur when heating or defrosting is desired?

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Go to Step  7

Go to Step 9

1. Start the engine.
2. Place the blower motor switch in the OFF position.
3. Place the HVAC control module in the OFF position.

Is the A/C compressor ON?

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Go to HVAC Compressor Clutch Does Not Disengage

Go to Step 8

Inspect the cooling system for the following conditions:

Did you find and correct the condition?

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Go to Step 21

Go to Step 9

Check the upper discharge, lower air temperature, and inside air temperature sensors for proper installation. Refer to Inside Air Temperature Sensor Replacement , Upper Discharge Air Temperature Sensor Replacement , Air Temperature Sensor Replacement - Lower .

Did you find and correct the condition?

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Go to Step 21

Go to Step 10

1. Install a scan tool.
2. 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. Install a thermometer near the upper outlet, lower outlet and inside air temperature sensors.
2. With a scan tool, observe the Upper Outlet, Lower Outlet and Inside Air Temp data parameters in the Heating and A/C Data list.

Do the temperatures vary by more than the specified range?

-3 to +3°C

(-5 to +5°F)

Go to Step 12

Go to Step 14

1. Turn the engine OFF.
2. Install a scan tool.
3. Cover the sunload sensor.
4. Start the engine.
5. Adjust driver side temperature to 22°C (72°F).
6. With a scan tool, observe the Solar Sensor data parameter in the Heating and Air Conditioning data list.

Does the scan tool indicate that the solar sensor parameter is greater than the specified value?

230 counts

Go to Step 13

Go to Step 16

1. Uncover the sunload sensor.
2. Direct a light source at the sunload sensor.

Do the counts change?

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System OK

Go to Step 16

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

Does the resistance measure near the Sensor Resistance Table?

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Go to Step 17

Go to Step 15

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?

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Go to Step  21

Go to Step 18

Inspect for poor connections at the harness connector of the sunload 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 21

Go to Step 19

Inspect for poor connections at the harness connector of the 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?

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Go to Step 21

Go to Step 20

Replace the temperature sensor. Refer to , Inside Air Temperature Sensor Replacement , Upper Discharge Air Temperature Sensor Replacement or Air Temperature Sensor Replacement - Lower .

Did you complete the replacement?

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Go to Step 21

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Replace the sunload sensor. Refer to Sun Load Sensor Replacement .

Did you complete the replacement?

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Go to Step 21

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Important: Perform the recalibration procedure for the HVAC control module.

Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

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Go to Step 21

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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 3