GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 Spark 🢒 HVAC 🢒 HVAC - Manual 🢒 Air Delivery Improper
Table 1: Improper Air Delivery or No Mode Shift

This procedure provides a test of all functions of the heater/defroster unit.

  1. Warm up the vehicle.
  2. Keep the engine running.
  3. Perform the tests outlined in the table below and look for the results indicated.

Mode Knob

Temperature Control

Blower Motor Switch

Blower Speed

Power Vent Outlet

Floor Outlet

Defrost Outlet

Side Window Outlet

Vent

Cold

OFF

OFF

No Airflow

No Airflow

No Airflow

No Airflow

Vent

Cold

4

High

Ambient Airflow

No Airflow

No Airflow

No Airflow

Floor

Cold to Hot

4

High

No Airflow

Cold to Hot Airflow

Minimum Cold to Hot Airflow

Minimum Cold to Hot Airflow

Defroster

Cold to Hot

4

High

No Airflow

Minimum Cold to Hot Airflow

Cold to Hot Airflow

Minimum Cold to Hot Airflow

If any of these settings does not produce the correct results, perform the Improper Air Delivery diagnostic procedure.

Improper Air Delivery or No Mode Shift

Step

Action

Yes

No

1

Verify the customer's complaint.

Are the customer's concerns verified?

Go to Step 2

System OK

2

Examine the affected door in the unit for proper cable attachment.

    • Inspect the cable connection to the door.
    • Inspect that the cable sheath is properly retained.

Is the cable connected properly?

Go to Step 4

Go to Step 3

3

Repair as necessary.

Is the repair complete?

System OK

--

4
  1. Disconnect the cable at the door.
  2. Inspect the range of the door travel and the effort required to move it.

Does the door move freely through its entire range of travel so that it can close at both ends of the range?

Go to Step 5

Go to Step 3

5

Inspect the travel of the Bowden cable by turning the control knob.

Is the cable travel OK?

Go to Step 6

Go to Step 7

6
  1. Reinstall the cable.
  2. Inspect the system using the Control Settings/Correct Results tests in this procedure.

Does the system perform properly?

System OK

Go to Step 9

7
  1. Inspect the cable attachment at the control.
  2. Inspect for a broken control.

Is there a problem with the cable attachment or the control?

Go to Step 8

Go to Step 9

8

Repair the cable attachment or control as necessary.

Is the repair complete?

System OK

Go to Step 9

9

Inspect the system using the Control Settings/Correct Results tests in this procedure.

Is the repair complete?

System OK

Go to Step 11

10

Inspect for airflow from the defroster or the vent outlets.

Is there high airflow from the defroster or the vent outlets?

Go to Step 10

Go to Step 12

11

Adjust the heater door at the floor and the vent door to get the proper airflow.

Is the repair complete?

System OK

--

12

Switch the mode knob to defrost.

Is the defroster airflow OK?

Go to Step 13

Go to Step 14

13
  1. Remove the heater outlet.
  2. Inspect the heater outlet for obstructions.
  3. Remove any obstructions in the heater outlet.

Is the repair complete?

System OK

--

14

Inspect the blower speeds for change in the airflow.

Does the blower speed increase as the control is turned from 1 to 4?

Go to Step 15

Go to Blower Motor Malfunction

15
  1. Inspect for obstructions in the system at the blower inlet.
  2. Remove any obstructions at the blower inlet.

Is the repair complete?

System OK

Go to Step 16

16
  1. Set the blower on 4.
  2. Rotate the temperature control from full hot to full cold.
  3. Listen for an airflow change.

Did the airflow change?

Go to Step 17

Go to Step 18

17
  1. Inspect the temperature door adjustment, the cables, the linkage, and the control.
  2. Adjust the temperature control to full hot.

Is the repair complete?

System OK

--

18
  1. Inspect the system for any obstruction between the blower and the system outlets.
  2. Remove any obstruction between the blower and the system outlets.

Is the repair complete?

System OK

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