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 - Manual

1. Turn ON the ignition, with the engine OFF.
2. Place the mode switch in any position except OFF.
3. Place the blower control in each speed position.

Does the blower motor operate correctly for each speed position?

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Go to Step 3

Go to Blower Motor Inoperative

Does the blower motor provide sufficient air flow?

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Go to Step 4

Go to Blower Motor Malfunction

1. Start the engine.
2. Place the mode switch in the vent position.
3. Place the blower motor switch in the maximum speed position.
4. Place the outside air switch in the ON position.
5. Place the recirculation switch in the ON position.

Does the recirculation door operate properly?

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Go to Step 5

Go to Air Recirculation Malfunction

Inspect the cooling system for the following conditions:

Did you find and correct the condition?

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Go to Step 18

Go to Step 6

1. Start the engine.
2. Place the mode switch in the OFF, VENT or HEAT positions.

Does the A/C compressor operate?

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Go to HVAC Compressor Clutch Does Not Disengage

Go to Step 7

1. Observe the drive shaft of the air temperature actuator.
2. Adjust the air temperature switch.

Does the air temperature actuator drive shaft rotate at all?

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Go to Step 8

Go to Step 9

Inspect the air temperature door and the air temperature actuator for the following conditions:

Did you find and correct the condition?

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Go to Step 18

Go to Heating Performance Diagnostic in Heating, Ventilation and Air Conditioning

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

Did you find and correct the condition?

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Go to Step 18

Go to Step 10

Test the ground circuit of the air temperature actuator for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 18

Go to Step 11

Test the air temperature door position signal circuit of the air temperature actuator for an open, high resistance, short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 18

Go to Step 12

12

Important:: Ensure that the HVAC control module connector is connected during this step in order to avoid misdiagnosis.

1. Turn ON the ignition, with the engine OFF.
2. Measure the voltage from the air temperature door position signal circuit of the air temperature actuator to a good ground.
3. Place the air temperature switch from the coldest position to the warmest position.

Does the voltage measure within the specified values with a smooth transition between cold and hot?

12 V at cold 0 V at hot

Go to Step 15

Go to Step 13

Inspect for poor connections at the harness connector of the air temperature actuator. 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 18

Go to Step 14

Inspect the air temperature door and the air temperature actuator for the following conditions:

Did you find and correct the condition?

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Go to Step 18

Go to Step 16

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 18

Go to Step 17

Replace the air temperature actuator. Refer to Air Temperature Actuator Replacement .

Did you complete the replacement?

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Go to Step 18

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

Did you complete the replacement?

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Go to Step 18

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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