Pinpoint Test C: Incorrect/Erratic Direction of Airflow From Outlet(s)
Climate Control System
Pinpoint Tests
Pinpoint Test C: Incorrect/Erratic Direction of Airflow From Outlet(s)
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.
This pinpoint test is intended to diagnose the following:
- Function selector switch
- Heater control valve
- Vacuum control motor
- Stuck or bound linkage or door
- Leaking or plugged vacuum hose
PINPOINT TEST C: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET(S)
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C1 CHECK THE SYSTEM AIRFLOW
- Ignition ON.
- 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 C2.
No
GO to C8.
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C2 CHECK THE VACUUM SUPPLY LINE FOR OBSTRUCTIONS
- NOTE: The 2 vacuum lines to the vacuum reservoir tank are not interchangeable.
- Disconnect the vacuum lines from the vacuum reservoir tank.
- Connect the Vacuum Pump from the Vacuum Pump Kit to the vacuum supply line and try to pull a vacuum. If the Vacuum Pump can pull a vacuum, the vacuum supply line is plugged. If the Vacuum Pump pulls a partial vacuum, the vacuum supply line is restricted.
- Is the vacuum supply line plugged or restricted?
Yes
REPAIR or INSTALL a new vacuum supply line. TEST the system for normal operation.
No
GO to C3.
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C3 CHECK THE VACUUM SUPPLY LINE FOR A LEAK
- NOTE: The vacuum supply line is grouped with other vacuum lines at a single intake manifold connection. Identify and plug the vacuum supply line only.
- Disconnect and plug the vacuum supply line at the intake manifold.
- Using the Vacuum Pump from the Vacuum Pump Kit, apply 51 kPa (15 in-Hg) of vacuum to the vacuum supply line.
- Does the vacuum supply line lose more than 3.37 kPa (1 in-Hg) of vacuum in one minute?
Yes
REPAIR or INSTALL a new vacuum supply line. TEST the system for normal operation.
No
GO to C4.
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C4 CHECK THE VACUUM RESERVOIR TANK
- NOTE: The A/C vacuum check valve is internal to the vacuum reservoir tank and cannot be serviced separately. This step confirms vacuum reservoir tank integrity and correct operation of the A/C vacuum check valve.
- Connect the Vacuum Pump from the Vacuum Pump Kit to the climate control assembly vacuum source port of the vacuum reservoir tank and apply 51 kPa (15 in-Hg) of vacuum.
- Does the vacuum reservoir tank lose more than 3.37 kPa (1 in-Hg) of vacuum in one minute?
Yes
INSTALL a new vacuum reservoir tank. TEST the system for normal operation.
No
GO to C5.
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C5 CHECK THE VACUUM RESERVOIR TANK FOR OBSTRUCTIONS
- Disconnect the Vacuum Pump from the Vacuum Pump Kit from the vacuum source port of the vacuum reservoir tank.
- NOTE: The A/C vacuum check valve is internal to the vacuum reservoir tank and cannot be serviced separately. This step confirms correct operation of the A/C vacuum check valve.
- Connect the Vacuum Pump to the vacuum supply port of the vacuum reservoir tank and try to pull a vacuum. If the Vacuum Pump can pull a vacuum, the vacuum reservoir tank is plugged. If the Vacuum Pump pulls a partial vacuum, the vacuum reservoir tank is restricted.
- Is the vacuum reservoir tank plugged or restricted?
Yes
INSTALL a new vacuum reservoir tank. TEST the system for normal operation.
No
GO to C6.
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C6 LEAK TEST THE VACUUM SOURCE LINE
- Disconnect the Vacuum Pump from the Vacuum Pump Kit from the vacuum reservoir tank.
- Disconnect the jumper vacuum harness from the function selector switch.
- Plug the black vacuum source line at the jumper vacuum harness.
- Connect the Vacuum Pump to the vacuum source line and apply 51 kPa (15 in-Hg) of vacuum.
- Does the vacuum source line lose more than 3.37 kPa (1 in-Hg) of vacuum in one minute?
Yes
REPAIR or INSTALL a new vacuum source line. TEST the system for normal operation.
No
GO to C7.
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C7 CHECK THE VACUUM SOURCE LINE FOR OBSTRUCTIONS
- Remove the plug from the black vacuum source line at the jumper vacuum harness.
- Using the Vacuum Pump from the Vacuum Pump Kit, try to pull a vacuum. If the Vacuum Pump can pull a vacuum, the vacuum source line is plugged. If the Vacuum Pump pulls a partial vacuum, the vacuum source line is restricted.
- Is the vacuum source line plugged or restricted?
Yes
REPAIR or INSTALL a new vacuum source line. TEST the system for normal operation.
No
GO to C8.
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C8 LEAK TEST THE FUNCTION SELECTOR SWITCH
- Disconnect the Vacuum Pump from the Vacuum Pump Kit from the vacuum source line.
- Connect the Vacuum Pump to the vacuum source port of the function selector switch and plug all other ports.
- Apply 51 kPa (15 in-Hg) of vacuum at each function selector switch position and check for vacuum drop.
- Does the function selector switch lose vacuum?
Yes
INSTALL a new function selector switch. TEST the system for normal operation.
No
GO to C9.
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C9 CHECK THE FUNCTION SELECTOR SWITCH FOR BLOCKAGE
- Connect a vacuum pump to the function selector switch vacuum supply port and try to pull a vacuum in each function selector switch position except DEFROST. If the vacuum pump can pull and hold a vacuum, the switch is plugged. If the vacuum pump pulls a vacuum that slowly decays, the hose is restricted.
- Is the switch plugged or restricted?
Yes
INSTALL a new function selector switch. TEST the system for normal operation.
No
GO to C10.
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C10 CHECK THE VACUUM HARNESS
- Disconnect the Vacuum Pump from the Vacuum Pump Kit and plugs from the function selector switch.
- Connect the Vacuum Pump to each vacuum line of the jumper vacuum harness, excluding the black vacuum source line, and apply 51 kPa (15 in-Hg) of vacuum.
- Does the vacuum harness line lose more than 3.37 kPa (1 in-Hg) of vacuum in one minute?
Yes
NOTE the vacuum harness line where the vacuum drops. GO to C11.
No
GO to C12.
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C11 CHECK THE VACUUM CONTROL MOTOR
- Disconnect the Vacuum Pump from the Vacuum Pump Kit from the jumper vacuum harness.
- Disconnect the vacuum line from the vacuum control motor of the vacuum circuit indicated in Step C10.
- Connect the Vacuum Pump to the vacuum control motor and apply 51 kPa (15 in-Hg) of vacuum.
- Does the vacuum control motor actuate and hold vacuum?
Yes
REPAIR or INSTALL a new vacuum harness. TEST the system for normal operation.
No
INSTALL a new vacuum control motor. TEST the system for normal operation.
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C12 CHECK THE PLENUM VACUUM HARNESS FOR OBSTRUCTIONS
- Disconnect the vacuum line from each vacuum control motor.
- Connect the Vacuum Pump from the Vacuum Pump Kit to each line of the jumper vacuum harness, excluding the black vacuum source line, and try to pull a vacuum. If the Vacuum Pump pulls a vacuum, the vacuum line is plugged. If the Vacuum Pump pulls a partial vacuum, the vacuum line is restricted.
- Is a vacuum line plugged or restricted?
Yes
REPAIR or INSTALL a new vacuum harness. TEST the system for normal operation.
No
GO to C13.
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C13 INSPECT THE INSTALLATION OF THE VACUUM CONTROL MOTORS
- Inspect the attachment of the vacuum control motor arms to the air distribution doors.
- Are the vacuum control motor arms connected to the air distribution doors or door levers?
Yes
REPAIR or INSTALL a new air distribution door. TEST the system for normal operation.
No
CONNECT the vacuum control motor arm to the air distribution door or door lever. TEST the system for normal operation.
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