Pinpoint Test C: Incorrect/Erratic Direction of Airflow From Outlets
Climate Control System
Pinpoint Tests
Pinpoint Test C: Incorrect/Erratic Direction of Airflow From Outlets
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 control.
This pinpoint test is intended to diagnose the following:
- Vacuum check valve
- Vacuum hose/harness
- Vacuum reservoir tank
- Vacuum control motor
- Function selector switch
- Air distribution door/linkage
PINPOINT TEST C: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLETS
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C1 CHECK THE SYSTEM AIRFLOW
- Ignition ON.
- Set the blower motor switch to HI.
- With the engine running, check the system airflow in each function selector switch position to determine which position(s) have incorrect airflow. Refer to the vacuum schematic.
- Is the airflow coming from the defroster nozzles in all of the positions?
Yes
GO to C2.
No
GO to C14.
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C2 CHECK THE VACUUM SUPPLY HOSE
- Ignition OFF.
- Check the vacuum supply hose to be sure that it is connected.
- Is the vacuum supply hose disconnected?
Yes
RECONNECT the vacuum supply hose. GO to C13.
No
GO to C3.
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C3 LEAK CHECK THE VACUUM TANK AND HOSES
NOTE: The in-line vacuum harness connector is located in the vehicle, below the instrument panel, on the passenger side.
- Disconnect: Intake Manifold Vacuum Hose.
- Disconnect: In-Line Vacuum Harness.
- Plug the vacuum supply hose at the intake manifold.
- Carry out a vacuum leak test on the vacuum tank, check valve and hoses.
- Connect the vacuum pump to the plenum vacuum harness connector.
- Apply a vacuum.
- Check for a vacuum leak.
- Is there leakage?
Yes
GO to C4.
No
GO to C9.
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C4 LEAK CHECK THE VACUUM SUPPLY HOSE
- Remove the evaporator core housing. Refer to Climate Control Evaporator Core Housing.
- Disconnect: Vacuum Supply Hose.
- Carry out a vacuum leak test on the vacuum supply hose.
- Plug one end of the hose.
- Connect the vacuum pump to the other end.
- Apply a vacuum.
- Check for a vacuum leak.
- Does the hose leak?
Yes
REPAIR or INSTALL a new vacuum supply hose. TEST the system for normal operation.
No
GO to C5.
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C5 INSPECT THE A/C VACUUM CHECK VALVE
- Disconnect: A/C Vacuum Check Valve.
- Inspect the A/C vacuum check valve for any obstructions and correct operation. Airflow through the A/C vacuum check valve must be directed toward the engine.
- Is the A/C vacuum check valve plugged or obstructed?
Yes
INSTALL a new A/C vacuum check valve. TEST the system for normal operation.
No
GO to C6.
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C6 LEAK TEST THE A/C VACUUM CHECK VALVE
- Carry out a vacuum leak test on the A/C vacuum check valve.
- Connect 2 hoses and a tee fitting to the outlet ports of the A/C vacuum check valve.
- Connect the tee fitting to the vacuum pump.
- Apply 51 kPa (15 in-Hg) of vacuum.
- If the vacuum loss exceeds 3.37 kPa (1 in-Hg) per minute, then remove the A/C vacuum check valve and carry out a vacuum leak test on the vacuum pump.
- Plug both of the hoses.
- Apply a vacuum.
- If the vacuum pump loses vacuum, then correct the problem and repeat this procedure.
- Does the A/C vacuum check valve leak?
Yes
INSTALL a new A/C vacuum check valve. TEST the system for normal operation.
No
GO to C7.
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C7 CHECK THE VACUUM RESERVOIR
- Disconnect: Vacuum Reservoir.
- Carry out a vacuum leak test on the vacuum reservoir tank.
- Connect the vacuum pump to the vacuum reservoir tank.
- Apply a vacuum.
- Check for a vacuum leak.
- Does the vacuum reservoir tank leak?
Yes
INSTALL a new vacuum reservoir tank. TEST the system for normal operation.
No
GO to C8.
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C8 CHECK THE SUPPLY HOSE
- Check the supply hose for a vacuum leak.
- Connect the vacuum pump to the supply hose of the plenum vacuum harness.
- Install a plug in the other end of the hose.
- Apply a vacuum.
- Check for a vacuum leak.
- Check the supply hose for a restriction or blockage.
- Remove the plug.
- Apply a vacuum.
- Check for a restriction or blockage.
- Does the supply hose have a leak, restriction or blockage?
Yes
REPAIR or INSTALL a new supply hose. TEST the system for normal operation.
No
GO to C9.
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C9 CHECK THE JUMPER VACUUM HARNESS SUPPLY HOSE
- Disconnect the jumper vacuum harness from the function selector switch.
- Check the jumper vacuum harness supply hose for a vacuum leak.
- Connect the vacuum pump to one end of the jumper vacuum harness supply hose.
- Install a plug in the other end of the hose.
- Apply a vacuum.
- Check for a vacuum leak.
- Check the jumper vacuum harness supply hose for a restriction or blockage.
- Remove the plug.
- Apply a vacuum.
- Check for a restriction or blockage.
- Does the jumper vacuum harness supply hose have a leak, restriction or blockage?
Yes
REPAIR or INSTALL a new jumper vacuum harness. TEST the system for normal operation.
No
GO to C10.
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C10 CHECK THE FUNCTION SELECTOR SWITCH
- Connect the jumper vacuum harness to the function selector switch.
- Carry out a vacuum leak test on each function selector switch position.
- Plug all of the vacuum hoses except for the function selector switch supply hose.
- Connect the vacuum pump to the function selector switch supply hose.
- Apply 51 kPa (15 in-Hg) of vacuum at each function selector switch position.
- Check for a vacuum drop exceeding 3.37 kPa (1 in-Hg) per minute.
- Does the vacuum drop more than 3.37 kPa (1 in-Hg) per minute?
Yes
NOTE which function selector switch position(s) leak. GO to C11.
No
GO to C15.
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C11 LEAK TEST THE CONTROL ASSEMBLY
- Disconnect the jumper vacuum harness from the function selector switch.
- Carry out a vacuum leak test on the function selector switch for the positions that were noted in Step C10.
- Plug the leaking control port(s), as noted in Step C10.
- Connect the vacuum pump to the function selector switch supply port.
- Select the corresponding function selector switch position.
- Apply 51 kPa (15 in-Hg) of vacuum.
- Check for a vacuum drop exceeding 1.68 kPa (1/2 in-Hg) per minute.
- Does the vacuum drop more than 1.68 kPa (1/2 in-Hg) per minute?
Yes
INSTALL a new function selector switch. TEST the system for normal operation.
No
GO to C12.
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C12 LEAK TEST THE PLENUM VACUUM HARNESS
- Disconnect the vacuum hose(s) that indicated a leak in Step C10 from the corresponding vacuum control motor.
- Carry out a vacuum leak test on each of the hose(s).
- Connect the vacuum pump to one end of the vacuum hose.
- Install a plug in the other end of the hose.
- Apply 51 kPa (15 in-Hg) of vacuum.
- Check for a vacuum leak.
- Do the vacuum hose(s) leak?
Yes
REPAIR or INSTALL a new plenum vacuum harness. TEST the system for normal operation.
No
CHECK the plenum vacuum harness connection. REPAIR or INSTALL a new plenum vacuum harness as necessary. TEST the system for normal operation.
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C13 EVALUATE THE SYSTEM AIRFLOW
- Ignition OFF.
- Check the airflow that was noted in Step C1 for each function selector switch position.
- Is the airflow in Step C1 correct for each function selector switch position?
Yes
GO to C14.
No
GO to C15.
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C14 ISOLATE THE LEAKING VACUUM CIRCUIT
- Ignition ON.
- With the engine running, set the blower motor switch to HI.
- Cycle the function selector switch to each function selector switch position during acceleration.
- Check for a variation in the system airflow for each function selector switch position during acceleration.
- Does the airflow go to defrost during engine acceleration?
Yes
GO to C19.
No
GO to C15.
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C15 REVIEW THE VEHICLE HISTORY
- Ignition OFF.
- Review the vehicle history to determine if the system operated correctly prior to the complaint.
- Did the system operate correctly prior to this complaint?
Yes
GO to C18.
No
GO to C16.
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C16 CHECK THE VACUUM HARNESSES
- Compare the colors on each vacuum hose to those shown on the vacuum schematic. Refer to the Vacuum Schematic.
- Do the vacuum hoses agree with what is shown on the vacuum schematic?
Yes
GO to C17.
No
CORRECT or INSTALL a new plenum vacuum harness or jumper vacuum harness. TEST the system for normal operation.
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C17 CHECK THE VACUUM CIRCUIT
- Inspect each vacuum hose to determine if it is pinched or kinked.
- Are any of the vacuum hoses pinched or kinked?
Yes
REPAIR the damaged vacuum hose(s) or INSTALL a new plenum vacuum harness. TEST the system for normal operation.
No
GO to C18.
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C18 CHECK THE VACUUM CIRCUIT CONNECTIONS
- Check vacuum hose connections to determine if any are disconnected or partially connected.
- Are any of the vacuum hoses disconnected or partially connected?
Yes
RECONNECT the vacuum hose(s). TEST the system for normal operation.
No
GO to C19.
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C19 CHECK THE VACUUM HOSES
- Disconnect each suspected vacuum hose from the system.
- Carry out a vacuum leak test on each suspected hose.
- Connect the vacuum pump to one end of the vacuum hose.
- Install a plug in the other end of the hose.
- Apply a vacuum.
- Check for a vacuum leak.
- Check each suspected hose for a restriction or blockage.
- Remove the plug.
- Apply a vacuum.
- Check for a restriction or blockage.
- Do any of the vacuum hose(s) have a leak, restriction or blockage?
Yes
REPAIR the vacuum hose(s) or INSTALL a new plenum vacuum harness or jumper vacuum harness. TEST the system for normal operation.
No
GO to C20.
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C20 CHECK THE VACUUM CONTROL MOTOR
- Disconnect the suspected vacuum control motor.
- Carry out a vacuum leak test on each of the suspected vacuum control motor(s).
- Connect the vacuum pump to the vacuum control motor(s).
- Apply a vacuum.
- Do any of the suspected vacuum control motor(s) leak?
Yes
INSTALL a new vacuum control motor(s). TEST the system for normal operation.
No
GO to C21.
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C21 CHECK THE VACUUM MOTOR INSTALLATION
- Check for correct attachment of the vacuum control motor arm to the air distribution door or air distribution door crank arm.
- Is the vacuum motor arm correctly attached to the air distribution door or air distribution door crank arm?
Yes
INSPECT for a binding or damaged air distribution door. REPAIR or INSTALL a new air distribution door as necessary. TEST the system for normal operation.
No
CONNECT the vacuum motor arm to the air distribution door or air distribution door crank arm. TEST the system for normal operation.
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