GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

1

Did you review the Air Delivery Description and Operation and the Air Temperature Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

2

  1. Start the engine.
  2. Turn the blower switch to any position except the OFF position.
  3. Turn the A/C switch to the ON position.

Does the condenser fan motor operate?

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

Go to Step 3

3

Connect a scan tool and command the condenser fan relay ON. If the relay energizes, the malfunction is in the fan motor, the wiring between the motor and G105 or high resistance in the relay contacts. If the relay does not energize, the malfunction is in the relay, the PCM, or the relay control wiring.

Does the condenser fan relay energize?

Go to Step 4

Go to Step 8

4

  1. Disconnect the condenser fan connector.
  2. Connect a test lamp across the condenser fan connector.
  3. Command the condenser fan ON with the scan tool.

Does the test lamp illuminate?

Go to Step 12

Go to Step 5

5

Test the condenser fan ground circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 6

6

Test the condenser fan supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 7

7

Test the condenser fan relay switch supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

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8

Test the condenser fan relay for an open in the coil between terminals 1 and 3.

Is the condenser fan relay coil open?

Go to Step 15

Go to Step 9

9

Test the condenser fan relay coil supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 10

10

Test the condenser fan relay control circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 11

11

  1. Disconnect the condenser fan relay connector.
  2. Connect a test lamp from the connector cavity 3 to B+.
  3. Command the condenser fan relay ON with the scan tool.

Does the test lamp illuminate?

--

Go to Step 13

12

Inspect for a poor connection or for a high resistance at the harness connector of the condenser fan. 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 17

Go to Step 14

13

Inspect for a poor connection or for a high resistance at the harness connector of the PCM. 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 17

Go to Step 16

14

Replace the condenser fan. Refer to Condenser Fan Replacement .

Did you complete the replacement?

Go to Step 17

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15

Replace the condenser fan relay. Refer to Condenser Fan Relay Replacement .

Did you complete the replacement?

Go to Step 17

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16

Replace the PCM. Refer to the following:

    •  Powertrain Control Module Replacement in Engine Controls-2.0 L
    •  Powertrain Control Module Replacement in Engine Controls-2.5 L

Did you complete the replacement?

Go to Step 17

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17

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3