GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Use a test lamp, connected to B+, in order to backprobe the heater-A/C control harness connector terminal D1 (circuit 61)

Does the test lamp light?

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Go to Step 3

Go to Step 2

2

Locate and repair a poor connection, or an open in circuit 61 (YEL) between the heater-A/C control harness connector terminal D1 and S258.

Is the repair complete?

--

System OK

--

3

Replace the heater-A/C control. Refer to Ambient Temperature Sensor Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

--

System OK

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