For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
1 | With the ignition switch in the ON position, turn the blower speed switch from OFF to each of the following settings:

1. LOW
2. MEDIUM 1
3. MEDIUM 2
4. HIGH
5. OFF

Does the blower motor speed increase at each speed level when you advance the selector switch towards HIGH, and decrease at each speed level when you advance the selector switch towards LOW?

Go to Step 2

Go to HVAC System Check

2 |

1. Inspect the engine coolant level.
2. Inspect the coolant pump drive belt tension. Refer to Drive Belt Replacement in Engine Mechanical.
3. Inspect the radiator and the heater hoses for leaks and kinks. Refer to Cooling System Leak Testing in Engine Cooling.
4. Inspect the radiator cap for proper operation. Refer to Cooling System Leak Testing in Engine Cooling.

Is the repair complete?

Go to Step 15

Go to Step 3

3 |

1. Inspect the thermostat for correct installation and operation. Refer to Thermostat Diagnosis and Engine Coolant Thermostat Replacement in Engine Cooling.
2. Replace thermostat as necessary. Refer to Engine Coolant Thermostat Replacement in Engine Cooling.

Is the repair complete?

Go to Step 15

Go to Step 4

4 |

1. Set the mode control to the HEAT position.
2. Set the blower speed to HIGH.
3. Set the temperature control to the hottest position.
4. Turn the ignition switch to the ON position.
5. Inspect for airflow from the heater outlet.

Is there high airflow from the heater outlet?

Go to Step 7

Go to Step 5

5 |

1. Inspect the mode control cable and the linkage operation.
2. Adjust the mode control cable as necessary. Refer to Mode Control Cable Replacement .

Is the repair complete?

Go to Step 15

Go to Step 6

6 |

1. Inspect for system obstructions between the blower and the system outlets. Refer to HVAC Module Assembly Replacement .
2. Inspect the system for obstructions at the blower inlet and at the plenum.
3. Repair as necessary.

Is the repair complete?

Go to Step 15

--

7 |

1. Turn the blower speed switch to HIGH.

Caution: The cooling system is pressurized when hot.

2. With the engine cold, remove the radiator cap.
3. Start the engine and idle until coolant flow is visible inside the radiator.
4. Install the radiator cap.
5. Using a thermometer, record the ambient air temperature.
6. Drive the vehicle at 48 km/h (30 mph) for a minimum of 20 minutes.
7. Using the thermometer, record the discharge air temperature at the heater outlet.
8. Using the following table, compare the heater outlet temperature with the ambient air temperature:

• | 54°C (130°F) at -18°C (0°F)

• | 59°C (139°F) at -4°C (25°F)

• | 64°C (147°F) at 10°C (50°F)

Is the heater outlet temperature within the specified values?

Go to Step 8

Go to Step 9

8 |

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

• | The instrument panel

• | The heater case

• | The front vents

2. Inspect for obstructions under the seats.
3. Repair as necessary.

Is the repair complete?

Go to Step 15

--

9 |

1. Turn the ignition switch to the LOCK position.
2. Test the temperature door operation by moving the temperature control quickly from the coldest position to the hottest position and back to the coldest position.

Do you hear the temperature door slamming at each end?

Go to Step 11

Go to Step 10

10 |

1. Inspect the temperature control cable and linkage operation.
2. Adjust the temperature control cable as necessary. Refer to Temperature Control Cable Replacement .

Is the repair complete?

Go to Step 15

--

11 |

1. Set the temperature control to the hottest position.
2. Start the engine.
3. Feel the inlet and the outlet heater hoses.

Does the inlet heater hose feel hot, and does the outlet heater hose feel warm?

Go to Step 13

Go to Step 12

12 |

1. Both hoses are warm.
2. Inspect for correct heater hose location. Refer to Heater Hoses Replacement .
3. Repair as necessary.

Is the repair complete?

Go to Step 15

--

13 |

1. Flush the heater core. Refer to Flushing in Engine Cooling.
2. Drain and fill the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
3. Set the temperature control to the hottest position.
4. Start the engine.
5. Feel the inlet and the outlet heater hoses.

Does the inlet heater hose feel hot, and does the outlet heater hose feel warm?

Go to Step 15

Go to Step 14

14 | Replace the heater core. Refer to Heater Core Replacement . Is the action complete? | Go to Step 15 | --
15 | Perform Function Test . Is the action complete? | System OK | --