GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you review the HVAC system operation and perform the necessary inspections?

--

Go to Step 2

Go to Symptoms

2

Check the HVAC fuse in the fuse block.

Is the HVAC fuse open?

--

Go to Step 3

Go to Step 4

3

Locate and repair a short to ground in circuit 41 (BRN). Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems..

Is the repair complete?

--

Go to Step 6

--

4

There is a fault in the vacuum source, vacuum actuators, vacuum hoses to actuators, linkage from actuators to values, or faulty valves. Refer to Vacuum System for further diagnosis.

Is the action complete?

--

Go to Step 6

Go to Step 5

5

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

Is the repair complete?

--

Go to Step 6

--

6

Verify that the system operates properly?

Does the system operate properly?

--

System OK

Go to Symptoms