GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Check the fuse B3-B4 in the fuse block.

Is the fuse open?

--

Go to Step 2

Go to Step 3

2

Locate and repair a short to ground in circuit 41.

Is the repair complete?

--

Go to HVAC Air Delivery System Check )

--

3

  1. Turn the ignition switch to the ON position.
  2. Use a test light, backprobe between the vacuum/electric solenoid harness connector terminal 6 and ground.

Does the test light illuminate?

--

Go to Step 5

Go to Step 4

4

Repair a poor connection or an open in circuit 41.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

5

  1. Press the VENT button on the HVAC control assembly.
  2. Press the RECIRC button to select inside air recirculation.
  3. Use a DMM to measure the voltage between B+ and the vacuum/electric solenoid harness connector terminal 2.

Is the measured voltage within the specified range?

9-14V

Go to Step 9

Go to Step 6

6

Check for poor connection or open in circuit 362.

Is there a poor connection or open in circuit 362?

--

Go to Step 7

Go to Step 20

7

Repair poor connection or open in circuit 362.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

8

Using a DMM, measure the voltage between B+ and the vacuum/electric solenoid harness connector terminal 4.

Is the measured voltage within the specified value?

9-14V

Go to Step 11

Go to Step 9

9

Check for poor connection or open in circuit 363.

Is there a poor connection or open in circuit 363?

--

Go to Step 10

Go to Step 20

10

Repair poor connection or open in circuit 363.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

11

Using a DMM, measure the voltage between B+ and the vacuum/electric solenoid harness connector terminal 5.

Is the measured voltage within the specified value?

9-14V

Go to Step 14

Go to Step 12

12

Check for poor connection or open in circuit 706.

Is there a poor connection or open in circuit 706

--

Go to Step 13

Go to Step 20

13

Repair poor connection or open in circuit 706

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

14

  1. Press the DEFROST mode button on the HVAC control assembly.
  2. Using a DMM, measure the voltage between B+ and the vacuum/electric solenoid harness connector terminal 1.

Is the measured voltage within the specified value?

9-14V

Go to Step 17

Go to Step 15

15

Check for poor connection or open in circuit 366.

Is there a poor connection or open in circuit  366?

--

Go to Step 16

Go to Step 20

16

Repair poor connection or open in circuit 366.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

17

Using a DMM, measure the voltage between B+ and the vacuum/electric solenoid harness connector terminal 3.

Is the measured voltage within the specified value?

9-14V

Go to Step 21

Go to Step 18

18

Check for poor connection or open in circuit 361.

Is there a poor connection or open in circuit 361?

--

Go to Step 19

Go to Step 20

19

Repair poor connection or open in circuit 361.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

20

Replace the HVAC control assembly

Refer to Control Assembly Replacement

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

21

  1. Turn the blower speed to the OFF position.
  2. Using a DMM, measure the voltage between B+ and the vacuum/electric solenoid harness connector terminal 1.

Is the measured voltage within the specified value?

9-14V

Go to Step 22

Go to Step 24

22

Check for a short to ground in circuit 366.

Is there a short to ground on circuit 366?

--

Go to Step 23

Go to Step 20

23

Repair short to ground in circuit 366.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

24

Using a DMM, measure the voltage between B+ and the vacuum/electric solenoid harness connector terminal 2.

Is the measured voltage within the specified value?

9-14V

Go to Step 25

Go to Step 27

25

Check for a short to ground in circuit 362.

Is there a short to ground on circuit 362?

--

Go to Step 26

Go to Step 20

26

Repair short to ground in circuit 362.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

27

Using a DMM, measure the voltage between B+ and the vacuum/electric solenoid harness connector terminal 3.

Is the measured voltage within the specified value?

9-14V

Go to Step 28

Go to Step 30

28

Check for a short to ground in circuit 361.

Is there a short to ground in circuit 361?

--

Go to Step 29

Go to Step 20

29

Repair short to ground in circuit 361.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

30

Using a DMM, measure the voltage between B+ and the vacuum/electric solenoid harness connector terminal 4.

Is the measured voltage within the specified value?

9-14V

Go to Step 31

Go to Step 33

31

Check for a short to ground in circuit 363.

Is there a short to ground in circuit 363?

--

Go to Step 32

Go to Step 20

32

Repair short to ground in circuit 363.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

33

Using a DMM, measure the voltage between B+ and the vacuum/electric solenoid harness connector terminal 5.

Is the measured voltage within the specified value?

9-14V

Go to Step 34

Go to Step 36

34

Check for a short to ground in circuit 706.

Is there a short to ground on circuit 706?

--

Go to Step 35

Go to Step 20

35

Repair short to ground in circuit 706.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

36

There is a fault in vacuum/electric solenoid, 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 HVAC Air Delivery System Check

--