Definition: Inspect for problems in the vacuum system that may result in a reduction of air flow from the air vents.

1. Turn the ignition switch to the ON position.
2. Idle the engine.
3. Move the rotary knob to each position.
4. Refer to the vacuum diagrams and operational charts for airflow, air door functioning, and vacuum circuits.

Does the air flow out of the proper outlet at each rotary knob position?

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System OK

Go to Step 2

1. Inspect the hose connections at the suspect air outlet(s).
2. Repair the hose connections, as necessary.

Was a repair necessary?

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System OK

Go to Step 3

1. Install a vacuum tee and gauge (with restriction) on the feed circuit line.
2. Idle the engine.
3. Read the vacuum. At all selector positions, normal vacuum is equivalent to manifold vacuum.

Is the vacuum less than normal?

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Go to Step 4

Go to Step 5

Repair the feed circuit connection at the engine.

Is the repair complete?

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System OK

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1. Install a vacuum tee and gauge at the vacuum reservoir outlet.
2. Idle the engine.
3. Read the vacuum.

Is the vacuum less than normal?

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Go to Step 6

Go to Step 8

1. Inspect for a bad connection of the reservoir line to the vacuum reservoir.
2. Repair the connection, if necessary.

Was a repair necessary?

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System OK

Go to Step 7

Replace the vacuum reservoir.

Is the repair complete?

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System OK

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1. Place the rotary knob in the malfunctioning position.
2. Inspect for vacuum at the pertinent vacuum actuator.

Does the actuator have vacuum?

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Go to Step 9

Go to Step 10

Replace the mode selector control switch.

Is the repair complete?

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System OK

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1. Determine if the actuator door is mechanically bound.
2. Repair as necessary.

Was a repair necessary?

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System OK

Go to Step 11

Replace the actuator door.

Is the repair complete?

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System OK

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