Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

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Test H

PINPOINT TEST H: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET(S) - MANUAL CLIMATE CONTROL


Test H1:






Test H2-H4:






Test H5-H6:






Test H7-H8:






Test H9-H10:






Test H11-H12:






Test H13-H15:






Test H16:






Normal Operation
Under normal operation, the function selector switch is provided vacuum from the engine. When a position is selected, vacuum is applied to the desired vacuum control motor that is connected to the mode door you want to control.

Possible Causes
- Function selector switch.
- Heater control valve.
- Vacuum control motor.
- Stuck or bound linkage or door.
- Leaking or plugged vacuum hose.