GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Astro - 4WD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Auxiliary 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 auxiliary heater or A/C blower motor.

    2.

  2. This step determines if the problem is in the auxiliary heater or A/C blower motor switch.

    3.

  3. This step tests for a short to voltage in the auxiliary heater or A/C blower motor supply circuit.

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The auxiliary blower motor is ON while the auxiliary mode switch is in the OFF position.

1

Did you review the auxiliary Heat or A/C 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 auxiliary heat or A/C 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

  1. Turn OFF the ignition.
  2. Disconnect the auxiliary heat or A/C blower motor switch connector.
  3. Turn ON the ignition, with the engine OFF.

Is the blower motor OFF?

Go to Step 8

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the auxiliary heat or A/C blower motor resistor assembly connector.
  3. Connect the auxiliary heat or A/C blower motor switch connector.
  4. Turn ON the ignition, with the engine OFF.

Is the blower motor OFF?

Go to Step 6

Go to Step 5

5

Test the auxiliary blower motor supply voltage circuit of the auxiliary blower motor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

--

6

Test the LO, MED and HI auxiliary blower motor speed control circuits for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 7

7

Inspect for poor connections at the harness connector of the appropriate auxiliary 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 11

Go to Step 9

8

Inspect for poor connections at the harness connector of the appropriate auxiliary blower motor switch. 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 11

Go to Step 10

9

Replace the appropriate auxiliary blower motor resistor assembly. Refer to Auxiliary Air Conditioning Blower Motor Resistor Replacement or Auxiliary Heater Blower Motor Resistor Replacement in HVAC Systems-Manual.

Did you complete the replacement?

Go to Step 11

--

10

Replace the rear Heat or A/C switch. Refer to Heater and Air Conditioning Control Blower Switch Replacement or Heater Control Blower Switch Replacement in HVAC Systems-Manual.

Did you complete the replacement?

Go to Step 11

--

11

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2