For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Observe the blower motor operation. Is the blower motor functioning at all? | Go to Step 3 | Go to Blower Motor Inoperative
3 | Use the blower push switch to cycle the blower through its different speeds. Does the motor function at different speeds? | Go to Step 4 | Go to DTC 6
4 |

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

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

Go to Step 6

Go to Step 5

5 |

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

Is the heater operating?

System OK

Go to Step 8

6 | Observe the air mix door motor (AMD) 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 functioning properly? | Go to Step 7 | Go to DTC 4
7 | Perform the checks found in HVAC preliminary checks. Refer to HVAC Preliminary Checks . Is the system operating normally now? | System OK | Go to Step 8
8 |

1. Place the controller in the AUTO mode.
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?

Go to Step 11

Go to Step 9

9 | Inspect the intake hose for the in-car sensor. Is the hose in good condition? | Go to Step 11 | Go to Step 10
10 | Repair or replace the intake hose. Is the repair complete? | System OK | --
11 | 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 12 | Go to Step 13
12 | Repair or replace the sensor, the wiring, or the controller as required. Is the repair complete? | System OK | --
13 | 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 14 | Go to Step 15
14 | Repair or replace the sensor, the wiring, or the controller, as required. Is the repair complete? | System OK | --
15 | 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 14 | Go to Step 16
16 | Perform the coolant temperature sensor test. Is the coolant temperature sensor malfunctioning? | Go to Step 17 | Go to Step 18
17 | Replace the coolant temperature sensor. Is the repair complete? | System OK | --
18 | Replace the air temperature controller (ATC). Refer to Heater and Air Conditioning Control Replacement . Is the repair complete? | System OK | --