Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

Inspect the coolant level.

Is the coolant level correct?

Go to Step 4

Go to Step 3

Add coolant as needed.

Did you correct the condition?

System OK

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Observe the blower motor operation.

Is the blower motor functioning at all?

Go to Step 5

Blower Motor Inoperative

Use the blower push switch to cycle the blower through its different speeds.

Does the motor function at different speeds?

Go to Step 6

Go to DTC 6

1. Run the blower and operate the MODE push switch manually.
2. Check for airflow out the various outlets.

Does the air flow from the different outlets as it should?

Go to Step 8

Go to Step 7

1. Remove the heater outlet and inspect for obstructions.
2. Remove any obstructions found.

Is the heater operating?

System OK

Go to Step 8

Observe the air mix door (AMD) motor while changing the temperature setting from 18-32°C (64-90°F) and then from 32-18°C (90-64°F).

Is the AMD motor adjusting to temperature properly?

Go to Step 9

Go to DTC 4

Inspect the coolant hoses for leaks or kinks.

Are the coolant hoses in good condition?

Go to Step 11

Go to Step 10

Repair any problem with the coolant hoses.

Is the heater operating?

System OK

Go to Step 11

Inspect the surge tank cap.

Is the surge tank cap in good condition?

Go to Step 13

Go to Step 12

Repair or replace the surge tank cap as needed.

Is the heater operating?

System OK

Go to Step 13

1. Set the A/C switch to OFF.
2. Set the temperature control to 32°C (90°F).
3. Set the blower motor speed to full high, all segments illuminated on the display.
4. Remove the surge tank cap.
5. Start the vehicle and run the engine at idle.
6. Watch for the flow of the coolant when the thermostat opens.

Does the coolant flow?

Go to Step 15

Go to Step 14

1. Inspect for the following conditions:

•	A faulty thermostat

•	A failed coolant pump impeller

•	A restriction in the cooling system

2. Make repairs as needed.

Is the repair complete?

System OK

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Inspect the temperature of the heater inlet and outlet hoses by feel.

Is the heater inlet hose hot and the outlet hose warm?

Go to Step 17

Go to Step 16

Back flush or replace the heater core.

Is the repair complete?

System OK

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Inspect the vehicle for cold air leaks at the following locations:

Are any leaks found?

Go to Step 19

Go to Step 18

Repair any cold air leaks.

Is the repair complete?

System OK

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Inspect the coolant temperature sensor.

Is there a problem indicated in the sensor, the sensor wiring or the controller?

Go to Step 20

Go to Step 21

Repair or replace the sensor, the wiring, or the controller as required.

Is the repair complete?

System OK

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Inspect the in-car sensor. Refer to DTC 1 .

Is there a problem indicated in the sensor, the sensor wiring, or the controller?

Go to Step 20

Go to Step 22

Inspect the ambient air temperature sensor. Refer to DTC 2 .

Is there a problem indicated in the sensor, the sensor wiring, or the controller?

Go to Step 20

Go to Step 23

Inspect the sun sensor. Refer to DTC 5 .

Is there a problem indicated in the sensor, the sensor wiring, or the controller?

Go to Step 20

Go to Step 24

Replace the automatic temperature controller (ATC). Refer to Heater and Air Conditioning Control Replacement .

Is the repair complete?

System OK

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