For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you perform the function test? | Go to Step 2 | Go to Function Test
2 | 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. Return the switch to OFF

Does the blower motor speed increase at each speed level when the selector switch is moved towards HIGH, and then decrease at each speed level when the selector switch is moved towards LOW?

Go to Step 3

Go to Symptoms - HVAC Systems - Manual

3 |

1. Inspect the engine coolant level. Refer to Coolant Concentration Testing in Engine Cooling.
2. Inspect the coolant pump drive belt tension.
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.
5. Repair as necessary.

Is the repair complete?

Go to Function Test

Go to Step 4

4 |

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

Is the repair complete?

Go to Function Test

Go to Step 5

5 |

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 ON.
5. Inspect for airflow from the heater outlet.

Is there high airflow from the heater outlet?

Go to Step 8

Go to Step 6

6 |

1. Inspect the mode door control cable and the linkages.
2. Adjust the mode control cable as necessary. Refer to Mode Control Cable Adjustment .

Is the repair complete?

Go to Function Test

Go to Step 7

7 |

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

Is the repair complete?

Go to Function Test

--

8 |

1. Turn the blower speed switch to HIGH.
2. Turn the temperature to full hot.

Caution: The cooling system is pressurized when hot.

3. With the engine cold, remove the radiator cap.
4. Start the engine and idle until coolant flow is visible inside the radiator.
5. Install the radiator cap.
6. Drive the vehicle at 48 km/h (30 mph) for a minimum of 20 minutes.
7. Using a thermometer, record the ambient air temperature.
8. Using the thermometer, record the discharge air temperature at the heater outlet.
9. 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)

• | 68°C (155°F) at 24°C (75°F)

Is the heater outlet temperature within the specified values?

Go to Step 9

Go to Step 10

9 |

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 Function Test

--

10 |

1. Turn the ignition switch to LOCK.
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.

Did you hear the temperature door slamming at each end?

Go to Step 12

Go to Step 11

11 |

1. Inspect the temperature control cable and the linkages.
2. Adjust the temperature control cable as necessary. Refer to Temperature Control Cable Adjustment .

Is the repair complete?

Go to Function Test

--

12 |

1. Set the temperature control to the hottest position.
2. Start the engine.
3. Feel the inlet and the outlet heater hoses. The air temperature around the hoses must be at least 29°C (85°F).

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

Go to Step 14

Go to Step 13

13 |

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

Is the repair complete?

Go to Function Test

--

14 |

1. Flush the heater core. Refer to Flushing and Cooling System Draining and Filling in Engine Cooling.
2. Set the temperature control to the hottest position.
3. Start the engine.
4. 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 Function Test

Go to Step 15

15 | Replace the heater core. Refer to Heater Core Replacement . Is the repair complete? | Go to Function Test | --