GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Air Delivery Improper

Circuit Description

The heater and A/C programmer will direct the blended air in one of several air delivery modes. The side window outlets receive the airflow during all of the modes of the operation. The heater and A/C programmer directs air to the other outlets by energizing specific vacuum valves. This feeds the appropriate combination of mode valve actuators. The heater and A/C programmer determines the proper air delivery mode based upon the following factors:

    • Current program number
    • Control panel setting
    • Set temperature
    • Low side temperature
    • Coolant temperature
    • Ambient air temperature
    • Sun load

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This test inspects the air inlet valve (door).

    2.

  2. This test inspects the DOWN part of the UP-DOWN valve (door).

    3.

  3. This test inspects the UP part of the UP-DOWN valve (door).

    4.

  4. This test inspects the A/C side of the A/C-defrost valve (door).

    5.

  5. This test inspects the defrost side of the A/C-defrost valve (door).

Step

Action

Value(s)

Yes

No

1

  1. Turn the engine ON.
  2. Select HI BLOWER.
  3. Connect the Scan Tool .
  4. Use the Scan Tool in order to command recirculation door movement.

Does the recirculation door operate?

--

Go to Step 2

Go to Step 3

2

Using the Scan Tool , select AIR DOWN.

Is most of the air flowing from the heater (floor) vents, with only a small bleed out of either the defrost vents or the A/C vents?

--

Go to Step 7

Go to Step 4

3
  1. Remove the programmer vacuum hose connector.
  2. Measure the vacuum on the black hose.

Is the vacuum less than the specified value?

10 in Hg

Go to Step 14

Go to Step 13

4

Attach a hand held vacuum pump to the YEL CKT.

Does the vacuum pump hold vacuum?

--

Go to Step 5

Go to Step 6

5
  1. Inspect for a stuck up/down valve or actuator.
  2. Inspect for the proper hose routing. If the routing is OK, replace the heater and A/C programmer. Refer to Programmer Replacement .

Is the repair complete?

--

Go to Step 16

--

6

Repair the leaking hose or the actuator.

Is the repair complete?

--

Go to Step 16

--

7

Using the Scan Tool , select A/C DEFROST.

Is most of the air flowing from the the A/C vents or the defrost vents, with only a small bleed from the heater vents?

--

Go to Step  8

Go to Step 9

8

Is most of the air out of the defroster vents?

--

Go to Step 10

Go to Step 11

9

Attach the hand held vacuum pump to the RED CKT.

Does the pump hold vacuum?

--

Go to Step 5

Go to Step 6

10

Using the Scan Tool , select AIR UP.

Is most of the air flowing from the A/C vents with only a small bleed out of the defroster vents?

--

System OK

Go to Step 12

11
  1. Inspect for a stuck A/C-defrost valve (door) or actuator.
  2. Inspect for proper hose routing. If the hose routing is OK, replace the heater and A/C programmer. Refer to Programmer Replacement .

Is the repair complete?

--

Go to Step 16

--

12

  1. Repair the leaking hose or actuator.
  2. Inspect for a stuck A/C-defrost valve (door) or actuator.
  3. Inspect for proper hose routing.

Is the repair complete?

--

Go to Step 16

--

13

Attach the hand held vacuum pump to the ORN CKT.

Does the pump hold vacuum?

--

Go to Step 15

Go to Step 6

14

Repair the vacuum source.

Is the repair complete?

--

Go to Step 16

--

15
  1. Inspect for a stuck inlet valve (door) or actuator.
  2. Inspect for proper hose routing. If OK, replace the heater and A/C programmer. Refer to Programmer Replacement .

Is the repair complete?

--

Go to Step 16

--

16
  1. Clear the DTCs.
  2. Verify that the system is operating properly.

Did you clear the DTCs and verify the operation?

--

System OK

--