GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Was the Heater Blower Controls System Check performed?

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Go to Step 2

Go to Heater Blower Controls System Check

2

  1. Place the heater and A/C controller mode switch in the Heat position.
  2. Place the heater and A/C controller blower motor switch in the Medium 2 position.
  3. Disconnect the blower motor resistor/relay connector.
  4. Place the ignition switch in the RUN position.
  5. Connect a unpowered test lamp between the blower motor resistor/relay connector, cavity F for CKT 72 (LT BLU), and ground.

Does the test lamp light?

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Go to Step 3

Go to Step 4

3

Replace the blower motor resistor/relay.

Refer to Blower Motor Resistor Replacement .

Is the repair complete?

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Go to Heater Blower Controls System Check

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4

  1. Disconnect the heater and A/C controller C2 connector.
  2. Connect a J 39200 between the heater and A/C controller pin C, and pin G.

Is continuity present?

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Go to Step 5

Go to Step 6

5

Repair the open in CKT 72 (LT BLU).

Refer to Wiring Repairs .

Is the repair complete?

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Go to Heater Blower Controls System Check

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6

Replace the heater and A/C controller.

Refer to Control Assembly Replacement .

Is the repair complete?

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Go to Heater Blower Controls System Check

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