GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Engine Cooling Schematics , HVAC Schematics , for the Automatic System or HVAC Schematics for the Manual System

Connector End View Reference: Cooling System Connector End Views

DEFINITION: One or both engine cooling fan motors run continuously in high or low speed.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Turn ON the ignition, with the engine OFF.

Are one or both cooling fans ON?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3

Are both cooling fans running continuously?

Go to Step 4

Go to Step 6

4

Are both cooling fans running continuously in high speed?

Go to Step 5

Go to Step 7

5

Test the low reference circuit of the A/C refrigerant pressure sensor for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 14

6

Remove the cool fan 3 relay.

Did the right cooling fan turn OFF?

Go to Step 10

Go to Step 8

7

Remove the cool fan 1 relay.

Did the cooling fans turn OFF?

Go to Step 12

Go to Step 9

8

Remove the cool fan S/P relay.

Did the right cooling fan turn OFF?

Go to Step 13

Go to Step 11

9

Repair the short to voltage in the left cooling fan motor supply voltage circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 18

--

10

Repair the short to voltage in the left cooling fan low reference circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 18

--

11

Repair the short to voltage in the right cooling fan motor supply voltage circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 18

--

12

Inspect for poor connections at the cool fan 1 relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 15

13

Inspect for poor connections at the cool fan S/P relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 16

14

Inspect for poor connections at the A/C refrigerant pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 17

15

Replace the cool fan 1 relay.

Did you complete the replacement?

Go to Step 18

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16

Replace the cool fan S/P relay.

Did you complete the replacement?

Go to Step 18

--

17

Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement .

Did you complete the replacement?

Go to Step 18

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18

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2