For 1990-2009 cars

### Circuit Description

The Blower Controls System Check is an organized approach to identify problems associated with the heater & A/C control and blower controller. This check must be the starting point for any blower controls complaint, and will direct you to the next logical step in diagnosing the complaint. The heater and A/C control is a very reliable component and is not likely the cause of the malfunction. Most system complaints are linked to faulty wiring and connectors, and occasionally to components. Understanding the computer system and using the tables correctly will reduce diagnostic time and prevent unnecessary parts replacement.

### Diagnostic Aids

• | The following conditions may result in an intermittent operation of the heater and A/C control with no DTC stored:

- | Any condition which results in the interruption of power to the heater and A/C control.

- | Out of range battery or ignition voltage

- | A loose or damaged ground(s)

• | An intermittent failure in the electronic system may be very difficult to detect and to accurately diagnose. A good description of the complaint may be very useful in locating an intermittent malfunction. Faulty electrical connections or wiring causes most intermitting problems. When an intermitting condition is suspected, check the suspected circuits for the following conditions:

- | Poor mating of connector halves or backed out terminals

- | Improperly formed or damaged terminals

- | Wire chafing

- | Poor wire to terminal connections

- | Dirty or corroded terminals

- | Damage to connector bodies

• | If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur. Perform a thorough inspection of all related wiring and connectors pertaining to the history DTC stored.

### Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. Selecting Defrost after the engine reaches operating temperature, allows the blower motor to operate at maximum speed.

2. This steps checks the remaining blower speeds.

#### Blower Controls System Check

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 |

1. Connect the scan tool to the Data Link Connector (DLC).
2. Attempt to establish communications with the heater and A/C control.

Does the scan tool display data?

--

Go to Step 2

Go to Step 5

2 | Are any current DTCs displayed? | -- | Go to DTC Table | Go to Step 3
3 | Are any history or intermittent DTCs displayed? | -- | Go to Step 4 | Go to Step 6
4 |

1. Refer to the Diagnostic Aids of the DTC that is displayed.
2. Try performing the tests listed of that particular DTC while moving the harness wiring and connectors, this can often cause the malfunction to occur.

Was a problem found and repaired?

--

System OK

--

5 | Refer to Scan Tool Does Not Comm. with Heater and A/C Ctrl in Data Link Communications to diagnose condition. Was a repair made? | -- | Go to Step 1 | --
6 |

1. Remove the scan tool.
2. Start the engine and let it reach operating temperature.
3. Select Defrost on the heater & A/C control.

Does the blower motor operate on high speed?

--

Go to Step 7

Go to Blower Motor Inoperative at Any Speed

7 |

• | Decrease the blower speed to the next lowest speed.

• | Continue to decrease the blower speed in steps to the lowest.

Do all the 5 blower speeds operate properly?

--

Go to Step 8

Go to Blower Has High Speed Only

8 | Turn Off all the functions on the heater and A/C control. Does the blower motor continue to operate? | -- | Go to Blower Motor Always On | System OK