Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

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

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, observe the current DTC list for the HVAC Module.

Does the scan tool display DTC B0408, B0409, B0419 or B0423?

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Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

Place the blower motor switch in each speed position.

Does the blower motor operate in any speed position?

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Go to Step 4

Go to Blower Motor Malfunction

Does the blower motor operate in each speed position?

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Go to Step 5

Go to Blower Motor Malfunction

1. Place the blower motor switch in the maximum speed position.
2. Place the mode controls in the BI-LEVEL position.
3. Alternately, place the recirculation switch in the outside air and recirculation positions.

Does the recirculation door move from the recirculation position to the ambient air position?

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Go to Step 6

Go to Air Delivery Improper

Place the passenger temperature in the OFF position.

Does the Too Hot in Vehicle concern occur when A/C cooling desired?

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Go to Step 7

Go to Step 9

7

Important: Ambient air temperature must be above 3°C (38°F).

1. Cover the sunload sensor.
2. Start the engine.
3. Open all panel outlets in order to allow maximum air flow.
4. Place the air temperature switch to the coldest position.
5. Place the mode switch in the VENT position.
6. Place the blower motor switch in the maximum speed position.
7. Ensure that the vent indicator is not illuminated.

Does the A/C compressor operate?

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Go to Step 8

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 26

Go to Step 9

Inspect the upper left, upper right, lower left, and lower right air temperature sensors for the following conditions:

Did you find and correct the condition?

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Go to Step 26

Go to Step 10

1. Turn ON the ignition, with the engine OFF.
2. Inspect for airflow through the inside air temperature assembly 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 14

1. Install a thermometer near the upper left, upper right, lower left, and lower right air sensors and the inside air temperature assembly.
2. With a scan tool, observe the Inside Air Temp. data parameter in the Instrument Panel Module Data list.

Does the scan tool indicate that the sensor temperatures are within the specifications at the thermometer temperatures?

-3 to +3°C (-5 to +5°F)

Go to Step 12

Go to Step 17

1. Turn the engine OFF.
2. Install a scan tool.
3. Cover the sunload sensor.
4. Start the engine.
5. Place the driver side temperature at 22°C (72°F).
6. With a scan tool, observe the Solar Sensor data parameter in the Instrument Panel Module data list.

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

224 Counts

Go to Step 13

Go to Step 19

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 19

1. Disconnect inside air temperature assembly.
2. Turn ON the ignition, with the engine OFF.
3. Connect a test lamp between the ignition 3 circuit of the inside air temperature assembly and the inside air temperature assembly control circuit of the inside air temperature assembly.

Does the test lamp illuminate?

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Go to Step 18

Go to Step 15

Test the ignition 3 voltage circuit of the inside air temperature assembly for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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Go to Step 26

Go to Step 16

Test the inside air temperature assembly control circuit of the inside air temperature assembly for the following conditions:

Did you find and correct the condition?

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Go to Step 26

Go to Step 20

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 21

Go to Step 18

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 .

Did you find and correct the condition?

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Go to Step 26

Go to Step 22

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

Did you find and correct the condition?

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Go to Step 26

Go to Step 23

Inspect for poor connections at the harness connector of the HVAC module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

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Go to Step 26

Go to Step 24

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 .

Did you find and correct the condition?

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Go to Step 26

Go to Step 25

Replace the appropriate temperature sensor. Refer to Inside Air Temperature Sensor Replacement .

Did you complete the replacement?

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Go to Step 26

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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 26

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Replace the HVAC module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

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Go to Step 26

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Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

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Go to Step 26

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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