Vacuum-actuated doors regulate airflow control through
the HVAC module. Outside air is either cooled or heated and then discharged
according to the control setting.
In case of vacuum line/harness leakage or hose collapse, replacing the
entire vacuum harness assembly is not necessary. Use the following procedure
in order to repair the hose:
- Cut the hose.
- Insert a plastic connector.
Use the following procedure in order to replace an entire hose:
- Cut the hose off at the connector.
- Attach a new hose directly to the vacuum solenoid control assembly.
Vacuum System
An engine vacuum is stored in the vacuum reservoir in the engine compartment.
The engine vacuum controls all air valves except the temperature valve. The
vacuum is routed by a vacuum switch in the control assembly to any of the
vacuum actuators. One vacuum actuator is linked to each air valve.
The mode control knob controls the vacuum switch in the control assembly.
The vacuum switch performs the following actions for each mode control knob
position:
| • | Directs the engine vacuum to specific hoses |
| • | Vents the remaining hoses to normal air pressure |
The following actions occur when a hose vents to normal air pressure:
| • | The vacuum actuator's internal spring expands. |
| • | The spring holds the associated air valve in one position. |
The force of the vacuum performs the following actions when vacuum routes
to the hose:
| • | Overcomes the internal spring pressure |
| • | Moves the air to the opposite extreme of the air's travel |
This process allows the control knob to position the air valves for
the selected operating mode.
Ducts and Outlets
A system of ducts and outlets directs air to the passenger compartment.
Inspect the following components for obstructions if poor air output exists:
The following items are obstructions:
| • | Objects that may have fallen into the ducts from the passenger
compartment |
