GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Test for a fault in the vacuum source, vacuum actuators, vacuum hoses to actuators, linkage from actuators to values, or faulty valves. Inspect the system for these conditions.

Were any leaks found?

--

Go to Step 2

Go to Step 3

2

Refer to Temperature Actuator Inoperative for further diagnosis.

Is the repair complete?

--

Go to Step 4

--

3

Replace the Heater A/C Control Module. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to Step 4

--

4

Verify that the system operates properly.

Does the system operate properly?

--

System OK

Go to Symptoms