GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C Sierra - 2WD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Blower Motor Always On

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step checks for continuous operation of the blower motor.

    2.

  2. This step tests for a short to voltage in the blower motor control circuits.

Step

Action

Yes

No

Schematic Reference : HVAC Schematics

DEFINITION: The blower motor is ON while the blower motor switch is in the OFF position,

1

Did you review the HVAC operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

2

  1. Turn ON the ignition, with the engine OFF.
  2. Place the mode selector to the vent position.
  3. Place the blower motor switch to the OFF position.

Is the blower motor OFF?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Important: The blower motor switch must remain in the OFF position during this step.

  1. Turn OFF the ignition.
  2. Disconnect the connector C1 to the blower motor resistor assembly.
  3. Turn On the ignition, with the engine OFF.
  4. Probe each blower motor control circuit with a test lamp that is connected to ground.

Did the test lamp illuminate while connected to any of the blower motor control circuits?

Go to Step 4

Go to Step 5

4

Test the appropriate blower motor control circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 6

5

Inspect for bad connections at the harness connectors of the blower motor resistor assembly. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 7

6

Inspect for bad connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 8

7

Replace the blower motor resistor assembly. Refer to Blower Motor Resistor Replacement in Heating, Ventilation and Air Conditioning.

Did you complete the replacement?

Go to Step 9

--

8

Replace the HVAC control module. Refer to Heater and Air Conditioning Control Replacement .

Did you complete the replacement?

Go to Step 9

--

9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2