Test Description
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers on the diagnostic table.
- 6: This step tests the output from the blower motor switch. Loss of blower motor switch output would indicate a malfunctioning switch or a circuit malfunction in the supply voltage to the switch.
- 7: There are two ignition 3 voltage circuits at the HVAC control module. Test the circuit that provides the supply voltage to the blower motor switch.
Blower Motor Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The blower motor is inoperative in all speed positions. |
|||
| 1 | Did you perform the HVAC Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - HVAC Systems - Manual |
| 2 |
|
Go to Blower Motor Malfunction | Go to Step 3 |
| 3 |
|
Go to Step 4 | Go to Step 6 |
| 4 | Connect a test lamp between the blower motor supply voltage circuit and the blower motor ground circuit. Does the test lamp illuminate? |
Go to Step 8 | Go to Step 5 |
| 5 | Test the ground circuit of the blower motor resistor assembly for an open or high resistance. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 16 | Go to Step 9 |
| 6 |
|
Go to Step 9 | Go to Step 7 |
| 7 |
|
Go to Step 11 | Go to Step 12 |
| 8 | Inspect for poor connections at the harness connector of the blower motor. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 16 | Go to Step 13 |
| 9 | Visually inspect the blower motor harness of the blower motor resistor assembly for an open. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 16 | Go to Step 10 |
| 10 | Inspect for poor connections at the harness connector of the blower motor resistor assembly. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 16 | Go to Step 14 |
| 11 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 16 | Go to Step 15 |
| 12 | Repair the ignition 3 voltage circuit of the blower motor switch. Refer to Wiring Repairs
in Wiring Systems. Did you complete the repair? |
Go to Step 16 | - |
| 13 | Replace the blower motor. Refer to Blower Motor Replacement (Delphi)Blower Motor Replacement (Visteon)
in Heating, Ventilation and Air Conditioning. Did you complete the replacement? |
Go to Step 16 | - |
| 14 | Replace the blower motor resistor. Refer to Blower Motor Resistor Replacement
in Heating, Ventilation and Air Conditioning. Did you complete the replacement? |
Go to Step 16 | - |
| 15 | Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? |
Go to Step 16 | - |
| 16 | Operate the system in order to verify the repair. Did you correct the condition? |
System OK | Go to Step 3 |