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Test 1: Improper/Erratic Airflow From Outlets

WARNING: This page is about a different car, the 2001 Mazda Tribute. However, it is still accessible from the selected car via links, so may be relevant.
  1. Start engine. Set blower motor switch to HI position. With engine at idle, check for proper airflow from each mode switch position. If airflow is from defrost outlets only in each function switch position, go to next step. If airflow is not from defrost outlets only, go to step  13.
  2. Turn ignition off. Ensure Black vacuum supply hose is connected between engine intake manifold and vacuum reservoir check valve. If hose is connected, go to next step. If hose is disconnected, reconnect hose and recheck system operation.
  3. Disconnect vacuum hose from vacuum reservoir. Using vacuum pump, apply vacuum to hose. If vacuum can be pulled, hose is plugged. If a partial vacuum can be pulled, hose is restricted. If hose is plugged or restricted, replace vacuum hose. Recheck system operation. If hose is not plugged or restricted, connect vacuum hose to reservoir and go to next step.
  4. Disconnect Black vacuum supply hose from intake manifold and vacuum reservoir. Plug intake end of hose. Connect vacuum pump to reservoir end. Apply vacuum and check for leaks. If hose leaks, replace supply hose. If hose does not leak, reconnect hose to intake manifold and go to next step.
  5. Start engine. Disconnect reservoir hose from vacuum check valve. Check for vacuum at check valve. If vacuum exists, go to next step. If vacuum does not exist, replace check valve. Recheck system operation.
  6. Turn ignition off. Disconnect vacuum hose from vacuum check valve. Connect check valve to vacuum pump. Apply 15 in. Hg of vacuum. If vacuum leaks down more than 1 in. Hg per minute, remove check valve and plug vacuum hoses. Apply 15 in. Hg to ensure pump and hoses are not cause of leak. If check valve loses more than 1 in Hg of vacuum per minute, replace vacuum check valve. Recheck system operation. If vacuum does not leak down more than 1 in. Hg per minute, reinstall vacuum check valve and hoses and go to next step.
  7. Disconnect vacuum hose from reservoir tank. Connect vacuum pump to vacuum reservoir tank. Apply vacuum and check for leak down. If reservoir leaks, replace vacuum reservoir assembly. Recheck system operation. If vacuum reservoir does not leak, go to next step.
  8. Disconnect A/C-heater function selector switch vacuum connector. Plug supply hose at intake manifold connector end. Attach vacuum pump and apply vacuum to check for leaks. If Black supply hose leaks, replace hose and recheck system operation. If supply hose does not leak, remove plug and reconnect vacuum hose. Go to next step.
  9. Disconnect in-line vacuum harness connector. Disconnect vacuum supply in-line connector. Plug all function selector switch vacuum ports except Black supply hose. Select each function position on function selector switch while applying 15 in. Hg of vacuum to Black hose port. See VACUUM DIAGRAMS . If vacuum drop exceeds 1 in. Hg per minute, note position(s) where vacuum leak occurs. Go to step  11. If system holds vacuum, reconnect in-line vacuum harness and go to next step.
  10. Disconnect function selector switch vacuum harness connector. Connect vacuum pump to function selector switch supply hose. Apply vacuum and check for leaks. If vacuum can be pulled, hose is plugged. If partial vacuum can be pulled, hose is restricted. If hose is plugged or restricted, replace vacuum harness. Recheck system operation. If hose is not plugged or restricted, reconnect function selector switch vacuum connector and go to next step.
  11. Disconnect function selector switch vacuum harness connector. Connect vacuum pump to supply port and plug port that indicated a leak in step  9. If vacuum drop exceeds 1 in. Hg per minute, replace function selector switch. If vacuum drop does not exceed 1 in. Hg per minute, go to next step.
  12. Plug one end of suspect vacuum hose that indicated a leak in step  9. Attach vacuum pump to other end and apply 15 in. Hg of vacuum. If there is leak at vacuum jumper harness connector, repair or replace vacuum jumper harness. Recheck system operation. If no leak is noted, replace function selector switch. Recheck system operation.
  13. Evaluate system airflow. If airflow is correct for each function selector switch for each position, go to next step. If airflow is not correct for each function selector switch, go to step  15.
  14. Check for correct airflow in each function selector position during engine speed acceleration. If airflow goes to defrost outlets in all function selector switch positions, go to next step. If airflow does not go to defrost outlets during acceleration, system is operating properly at this time.
  15. Compare vacuum hose color in vacuum harness with each connector on function selector switch vacuum connector. See VACUUM DIAGRAMS . If hose colors of vacuum harness and connector colors match, go to next step. If hose colors of vacuum harness do not match, replace vacuum harness. Recheck system operation.
  16. Check A/C vacuum circuit for pinched or kinked vacuum hose(s). See VACUUM DIAGRAMS . If any hose is pinched or kinked, reposition or replace hose. Recheck system operation. If hoses are okay, go to next step.
  17. Check each vacuum hose to ensure it is properly attached at all connections. If any vacuum hose is disconnected, reconnect hose and recheck system operation. If hoses are properly connected, go to next step.
  18. Disconnect function selector switch vacuum harness connector. Disconnect suspect hose at suspect vacuum motor. Plug one end and attach vacuum pump to other end. Apply vacuum and check for leaks. If leak exists, repair or replace hose. Recheck system operation. If hose is okay, go to next step.
  19. Disconnect hose from suspect vacuum control motor. Apply 15 in. Hg of vacuum to vacuum control motor. If vacuum drop exceeds 0.5 in. Hg per minute, replace vacuum control motor and recheck system operation. If vacuum drop is within limits, go to next step.
  20. Check attachment of vacuum control motor arm to damper door. If motor arm is properly attached to damper door, service damper door for binding. Recheck system operation. If motor arm is not properly attached to damper door, connect motor arm and recheck system operation.
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