Pinpoint Test A: Incorrect/Erratic Direction of Airflow From Outlet(s)
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.
Function selector switch
Heater control valve
Vacuum control motor
Stuck or bound linkage or door
Leaking or plugged vacuum hose
PINPOINT TEST A: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET(S)
A1 CHECK THE SYSTEM AIRFLOW
Key in ON position.
With the engine running, adjust the blower motor speed to maximum. Check for correct airflow in each function selector switch position at engine idle and during engine acceleration.
Is there airflow only from the defroster outlets under all conditions?
Yes: GO to A2.
No: GO to A8.
A2 CHECK THE VACUUM SUPPLY LINE FOR OBSTRUCTIONS
NOTE:The 2 vacuum lines to the vacuum reservoir tank are not interchangeable.
Fig. 4: Disconnecting Vacuum Lines From Vacuum Reservoir Tank
Disconnect the vacuum lines from the vacuum reservoir tank.
Connect the special tool to the vacuum supply line and try to pull a vacuum. If the special tool can pull a vacuum, the vacuum supply line is plugged. If the special tool pulls a partial vacuum, the vacuum supply line is restricted.
Is the vacuum supply line plugged or restricted?
Saturday, January 24th, 2009 AT 9:14 PM