GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 STS 🢒 Body 🢒 Wiring Systems 🢒 Blower Motor Always On

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The blower motor operates with the HVAC controls in the OFF position or the blower motor operates at high speed only.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
  1. Turn ON the ignition, with the engine OFF.
  2. Turn OFF the HVAC control module.

Is the blower motor OFF?

Go to Step 3

Go to Step 8

3
  1. Turn ON the HVAC control module.
  2. Operate the blower motor switch from minimum to maximum.

Does the blower motor only operate at high speed?

Go to Step 4

Go to Blower Motor Malfunction

4
  1. Turn OFF the ignition.
  2. Unplug the blower control processor.
  3. Turn ON the ignition.
  4. Turn ON the HVAC control module.
  5. With a test lamp connected to battery positive probe the blower motor speed control circuit.
  6. Operate the blower switch from minimum to maximum.

Does the test lamp intensity change?

Go to Step 6

Go to Step 5

5

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

Did you find and correct the condition?

Go to Step 11

Go to Step 8

6

Test the blower motor fan control circuit for a short to ground. 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 blower motor control processor. 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 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 11

Go to Step 10

9

Replace the blower motor control processor. Refer to HVAC Control Processor Replacement .

Did you complete the replacement?

Go to Step 11

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10

Replace the HVAC control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming.

Did you complete the replacement?

Go to Step 11

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11

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2