For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
DEFINITION: Improper air delivery.

• | Vacuum applied to the wrong actuator.

• | Vacuum leak.

1 | Were you sent here from Symptoms, or another diagnostic table? | Go to Step 18 | Go to Step 2
2 | Did the customer concern mention that the air discharges out the correct ducts at first, but then changes during higher engine RPM? | Go to Step 11 | Go to Step 3
3 | Cycle the HVAC controls through all the modes. Does the air come out of the selected outlet ducts now? | Go to Step 18 | Go to Step 4
4 |

1. Start the engine.
2. Take a vacuum reading at the manifold vacuum port that supplies vacuum to the HVAC controls.

Is there engine vacuum?

Go to Step 5

Go to Step 17

5 | Take a vacuum reading at the vacuum supply line at the HVAC control head. Is the vacuum reading the same as engine vacuum? | Go to Step 6 | Go to Step 9
6 | Take a vacuum reading at the output side of the HVAC control head, for the non-functioning mode setting. Refer to the vacuum schematic in HVAC Vacuum Schematics to determine the correct actuator operation. Is there vacuum at the output side of the HVAC control head? | Go to Step 7 | Go to Step 14
7 | Disconnect the actuator vacuum line and apply vacuum to the actuator. Did the actuator retract? | Go to Step 9 | Go to Step 8
8 | With the actuator disconnected, inspect the door for binding. Does the door move freely? | Go to Step 10 | Go to Step 15
9 | Inspect for leaking or collapsed vacuum lines. Are the vacuum lines leaking? | Go to Step 16 | Go to Step 13
10 | Replace the vacuum actuator. Refer to the appropriate repair:

• | Defroster Valve Actuator Replacement

• | Mode Actuator Replacement

• | Recirculation Actuator Replacement

Is the repair complete?

Go to Step 18

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11 | With the vacuum gage connected to the actuator vacuum line, turn the engine OFF. Does the system lose vacuum after turning OFF the engine? | Go to Step 12 | Go to Step 9
12 |

1. Disconnect the vacuum line from the HVAC control head.
2. With the vacuum gage connected, re-start the engine and take a reading and turn the engine OFF.

Does the system lose vacuum after turning OFF the engine?

Go to Step 13

Go to Step 14

13 | Replace the vacuum reservoir tank. Refer to Vacuum Tank Replacement . Is the repair complete? | Go to Step 18 | --
14 | Replace the HVAC control head. Is the repair complete? | Go to Step 18 | --
15 | Repair the binding door. Refer to the appropriate repair.

• | Defroster Door Replacement

• | Mode Door Replacement

• | Recirculation Door Replacement

Is the repair complete?

Go to Step 18

--

16 | Repair or replace the collapsed or leaking vacuum line. Is the repair complete? | Go to Step 18 | --
17 | Repair the no vacuum condition. Is the repair complete? | Go to Step 18 | --
18 | Cycle the HVAC controls through all modes to verify proper operation. Did you find correct the condition? | System OK | Go to Step 2