Pinpoint Test I: Incorrect/Erratic Direction Of Airflow From Outlets - Manual Climate Control
Climate Control System
Pinpoint Tests
Pinpoint Test I: Incorrect/Erratic Direction of Airflow From Outlets - Manual Climate Control
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 to be controlled.
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 I: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLETS - MANUAL CLIMATE CONTROL
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I1 CHECK THE SYSTEM AIRFLOW
- Ignition ON.
- With the engine running, set the blower motor speed to maximum.
- Check for proper airflow in each function selector switch position at engine idle and under acceleration.
- Is the airflow correct in each function selector switch position?
Yes
The system is operating normally.
No
If the airflow is from only the defrost outlet in all settings, GO to I2.
If the airflow is incorrect in one setting only or recirculate does not function, NOTE the non-functional setting. GO to I11.
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I2 CHECK FOR VACUUM AT THE CHECK VALVE
- Disconnect the vacuum check valve and connect the vacuum pump to the vacuum source line and check for manifold vacuum.
- Is manifold vacuum present at the check valve vacuum source line?
Yes
GO to I3.
No
REPAIR or INSTALL a new check valve vacuum source line. TEST the system for normal operation.
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I3 CHECK THE VACUUM CHECK VALVES FOR LEAKAGE
- Ignition OFF.
- Disconnect: A/C Vacuum Check Valve.
- Connect the vacuum pump to the open port on the vacuum check valve and attempt to pull a vacuum.
- Can a vacuum be pulled on the vacuum check valves?
Yes
GO to I4.
No
INSTALL a new vacuum check valve. TEST the system for normal operation.
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I4 CHECK THE VACUUM CHECK VALVES FOR BLOCKAGE
- Connect the vacuum pump to the opposite port on the vacuum check valve and attempt to pull a vacuum.
- Can a vacuum be pulled on the vacuum check valves?
Yes
GO to I5.
No
INSTALL a new vacuum check valve. TEST the system for normal operation.
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I5 CHECK THE VACUUM RESERVOIR LINE FOR LEAKS
- Disconnect the vacuum reservoir line at the vacuum reservoir.
- Plug the vacuum reservoir line at the vacuum reservoir connection.
- Leak test the vacuum reservoir line, using the vacuum pump.
- Does the vacuum reservoir line leak?
Yes
REPAIR or INSTALL a new vacuum reservoir line. TEST the system for normal operation.
No
GO to I6.
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I6 CHECK THE VACUUM RESERVOIR LINE FOR BLOCKAGE
- Unplug the vacuum reservoir line at the vacuum reservoir connection.
- Connect the vacuum pump to the vacuum reservoir line at the vacuum check valve connection and attempt to pull a vacuum.
- Can a vacuum be pulled on the vacuum reservoir line?
Yes
REPAIR or INSTALL a new vacuum reservoir line. TEST the system for normal operation.
No
GO to I7.
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I7 CHECK THE VACUUM RESERVOIR FOR A LEAK
- Connect the vacuum pump reservoir line to the vacuum reservoir.
- With the vacuum pump connected to the vacuum reservoir line, leak test the vacuum reservoir.
- Does the vacuum reservoir leak?
Yes
INSTALL a new vacuum reservoir. TEST the system for normal operation.
No
GO to I8.
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I8 CHECK THE FUNCTION SELECTOR SWITCH VACUUM SOURCE LINE FOR BLOCKAGE
- Disconnect the function selector switch vacuum connector.
- Connect the vacuum pump to the function selector switch vacuum source line and attempt to pull a vacuum.
- Can a vacuum be pulled on the function selector switch vacuum source line?
Yes
REPAIR or INSTALL a new function selector switch vacuum source line. TEST the system for normal operation.
No
GO to I9.
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I9 CHECK THE FUNCTION SELECTOR SWITCH VACUUM SOURCE LINE FOR LEAKS
- Plug the function selector switch vacuum source line at the vacuum check valve connection.
- Leak test the function selector switch vacuum source line using the vacuum pump.
- Does the function selector switch vacuum source line leak?
Yes
GO to I10.
No
GO to I15.
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I10 CHECK THE HEATER CONTROL VALVE VACUUM SWITCH
- Disconnect the vacuum harness from the heater control valve vacuum switch and plug the vacuum source port.
- Leak test the vacuum source line using the vacuum pump.
- Does the vacuum source line leak?
Yes
REPAIR or INSTALL a new vacuum source line. TEST the system for normal operation.
No
INSTALL a new heater control valve vacuum switch. TEST the system for normal operation.
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I11 CHECK THE VACUUM CONTROL MOTOR LINE FOR BLOCKAGE
- Ignition OFF.
- Disconnect the function selector switch vacuum connector.
- Disconnect the vacuum line from the appropriate vacuum control motor noted in Step I1.
- Connect the vacuum pump to the appropriate vacuum control motor line noted in Step I1, and attempt to pull a vacuum.
- Can a vacuum be pulled on the vacuum control motor line?
Yes
REPAIR or INSTALL a new vacuum harness. TEST the system for normal operation.
No
GO to I12.
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I12 CHECK THE VACUUM CONTROL MOTOR LINE FOR LEAKS
- NOTE: Vehicles NOT equipped with a heater control valve vacuum switch: if the recirculation vacuum control motor does not function, disconnect and plug the heater control valve connection.
- Plug the vacuum control motor line at the vacuum control motor connection.
- Leak test the vacuum control motor line using the vacuum pump.
- Does the vacuum control motor line leak?
Yes
REPAIR or INSTALL a new vacuum harness. TEST the system for normal operation.
No
GO to I13.
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I13 CHECK THE VACUUM CONTROL MOTOR FOR LEAKS AND CORRECT OPERATION
- Connect the vacuum pump to the appropriate vacuum control motor and pull a vacuum.
- Does the vacuum control motor operate and hold vacuum?
Yes
GO to I15.
No
GO to I14.
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I14 CHECK THE MODE DOOR LINKAGE AND MOVEMENT
- Inspect the mode door linkage and verify correct movement of the mode door.
- Is the mode door or mode door linkage broken, binding or otherwise obstructed?
Yes
REPAIR the mode door or mode door linkage as necessary. TEST the system for normal operation.
No
INSTALL a new vacuum control motor. TEST the system for normal operation.
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I15 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 switch is restricted.
- Is the switch plugged or restricted?
Yes
INSTALL a new function selector switch. TEST the system for normal operation.
No
GO to I16.
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I16 LEAK TEST THE FUNCTION SELECTOR SWITCH
- Disconnect: Function Selector Switch Vacuum Harness.
- Connect a vacuum pump to the function selector switch vacuum supply port and plug each control port.
- At each function selector switch position, apply 51 kPa (15 in-Hg) of vacuum.
- Does the vacuum drop exceed 3.37 kPa (1 in-Hg) per minute?
Yes
INSTALL a new function selector switch. TEST the system for normal operation.
No
The system is operating normally.
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