GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Replace the blower motor relay with a known good relay.

Does the blower motor operate properly?

--

Go to Step 2

Go to Step 3

2

Replace the blower motor relay.

Is the repair complete?

--

Go to HVAC Blower Controls System Check

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3

  1. Turn the ignition to the OFF position.
  2. Disconnect the blower motor connector.
  3. Use a test lamp in order to backprobe the underhood junction block connector C3 between terminal D9 and ground.

Does the test lamp light?

--

Go to Step 4

Go to Step 5

4

Repair the short to battery positive in CKT 52 between the heater A/C control assembly connector C1 terminal C and the underhood junction block connector C3 terminal D9. Refer to Wiring Repairs in wiring systems.

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--

5

  1. Remove the blower motor relay.
  2. Disconnect the underhood junction block connector C3.
  3. Use a test lamp connected to ground in order to probe the underhood junction block relay cavity 30 (CKT 65).

Does the test lamp light?

--

Go to Step 6

Go to Step 7

6

Replace the underhood junction block. Refer to Relay/Fuse Center Replacement

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--

7

  1. Reconnect the underhood junction block connector C3.
  2. Disconnect the blower motor connector.
  3. Use a test lamp connected to ground in order to backprobe the blower motor connector terminal B.

Does the test lamp light?

--

Go to Step 8

Go to Step 9

8

Repair the short to positive battery voltage in CKT 65 between the underhood junction block and the blower motor connector.

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--

9

Replace the heater A/C control assembly. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--