Test C: Improper/Erratic Airflow Direction
WARNING: This page is about a different car, the 1999 Lincoln Navigator and 1999 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
- Check System Airflow
Start engine and run at idle. Adjust blower speed, with blower override, to high speed. In turn, press each override button for MAX A/C, VENT, PNL/FLR, FLOOR, FLR/DEF, and DEF (defrost). Check airflow at each setting. If airflow is only from defrost outlets in all positions, go to next step. If airflow is from other than defrost outlets only, go to step 14) . - Check Vacuum Supply Hose
In engine compartment, check all vacuum hose fittings at intake manifold, A/C vacuum check valve, and power brake booster. If hose is disconnected or damaged at any of these points, repair or replace as needed. If hose connections are okay, go to next step. - Leak Check Vacuum Supply Hose
Disconnect intake manifold vacuum supply and vacuum check valve. Plug vacuum supply hose at intake manifold end. With a vacuum tester, check hose for leaks. If hose leaks, repair or replace hose. Retest system. If hose does not leak, go to next step. - Check Vacuum Support Hose For Blockage
Reconnect intake manifold vacuum hose. With vacuum tester on check valve end of vacuum supply hose, try to pull vacuum. If pump pulls vacuum, hose is plugged. If pump pulls partial vacuum, hose is restricted. If hose is plugged or restricted, replace blocked vacuum supply hose and retest system. If hose is not plugged or restricted, go to next step. - Check Vacuum Check Valve
Connect vacuum check valve to original installation. Start and run engine at idle. Check vacuum check valve for blockage by removing vacuum hoses (except intake supply) and check for vacuum. If vacuum is available at the port, go to next step. If vacuum is not available, replace vacuum check valve. Retest system. - Leak Check Vacuum Check Valve
Turn ignition off. Disconnect vacuum check valve. With vacuum tester, connect two test hoses via "T" fitting to both vacuum ports (except intake manifold port). Apply 15 in. Hg of vacuum. If vacuum leak-down exceeds 1 in. Hg per minute, remove check valve and leak test hoses. If hoses are okay, but check valve loses vacuum, replace vacuum check valve. Retest system. If vacuum check valve does not lose vacuum, go to next step. - Check Vacuum Reservoir Tank For Leakage
Connect vacuum check valve. Disconnect vacuum reservoir tank hose from vacuum check valve. Attach vacuum tester to vacuum reservoir tank hose. Apply vacuum and observe pump gauge for leakage. If reservoir leaks, replace A/C vacuum reservoir tank and retest system. If no leak is indicated, go to next step. - Check Plenum Vacuum Harness
Connect vacuum reservoir tank hose. Disconnect in-line vacuum harness. Plug vacuum harness supply hose after disconnecting it from vacuum check valve. See Fig 1. Use vacuum tester to test Black vacuum supply hose at plenum harness. If vacuum leak is present, repair or replace plenum vacuum harness. If no vacuum leak is present, go to next step. - Check EATC Supply Hose
Connect in-line vacuum harness connector. Disconnect EATC vacuum harness. Attach vacuum tester to Black vacuum supply hose at EATC vacuum harness. See Fig 2. Pull and hold vacuum. If hose indicates a vacuum leak, repair or replace vacuum harness. If supply hose does not indicate a leak, go to next step. - Check EATC Module For Leakage
Connect EATC vacuum harness connector. Disconnect in-line vacuum harness connector. Connect vacuum tester to Black vacuum hose and plug other hose ports at plenum vacuum harness. See Fig 3. At each manual override mode, apply 15 in. Hg vacuum and check for leakage. If leak-down rate exceeds 1 in. Hg per minute, note manual override selection where leaks occur and go to next step. If no vacuum leaks are indicated, go to step 12) . - Check Vacuum Harness For Leakage
Ensure ignition is off. Disconnect vacuum harness connector from EATC module. Disconnect and plug one end of hose corresponding to manual override position indicating leakage. Attach vacuum tester to other end of hose and apply 15 in. Hg of vacuum. If leakage is indicated, repair or replace vacuum harness and retest system. If no leakage is indicated in vacuum harness, replace EATC module and retest system. - Check Plenum Vacuum Harness For Leakage
Reconnect vacuum harness Black vacuum supply hose at vacuum check valve. Connect vacuum tester to Black hose in plenum vacuum harness. Try to pull vacuum. If hose is plugged or restricted, full to partial vacuum can be pulled. If hose is plugged or restricted, replace or replace plenum vacuum harness. Retest system. If hose is not plugged or restricted, go to next step. - Check EATC Vacuum Harness For Blockage
Connect in-line vacuum harness connector. Disconnect EATC module vacuum harness connector. Connect vacuum tester to Black hose and try to pull vacuum. If pump can pull full or partial vacuum, Black hose is plugged or restricted. If hose is plugged or restricted, replace vacuum harness and retest system. If hose is okay, go to step 17) . - Evaluate System Airflow
Start and run engine at idle. Perform system operation test and evaluate airflow at each selection. If airflow is correct for each manual override button pressed, go to next step. If airflow is not correct, note selection at which incorrect airflow occurred and go to step 21) . - Isolate Leaking Vacuum Circuit
Select each manual override position and note airflow as vehicle is accelerated. If airflow goes to defrost outlets during acceleration, go to step 2) . If airflow does not go to defrost during acceleration, go to next step. - Isolate Leaking Vacuum Circuit
Select each manual override position and note airflow as vehicle is accelerated. If airflow is correct at each manual override position, system is okay at this time. If airflow is not correct for each manual override position, go to step 21) . - Review Vehicle History
Determine if EATC system functioned properly prior to this concern. If system did function properly, go to step 20) . If system did not function properly prior to current concern, go to next step. - Check Vacuum Harness
Compare vacuum hose color in each vacuum harness. See Fig 4. If hose colors are correct, go to next step. If hose colors are incorrect, replace vacuum harness. Retest system. - Check Vacuum Hose
Disconnect any suspect hose. Plug one end and apply vacuum to other end. If hose leaks, repair or replace hose. Retest system. If hose is okay, go to next step. - Check A/C Vacuum Circuit
Perform visual inspection of all vacuum hoses and check for kinked or damaged hoses. If hoses are kinked or damaged, reposition, repair or replace hoses as needed. Retest system. If hoses are okay, go to next step. - Check Vacuum Circuit Connections
Turn ignition off. Check each vacuum hose connection corresponding to manual override selection noted in previous step. If hose is disconnected, reconnect hose. Retest system. If hoses are properly connected, go to next step. - Check Plenum Hoses
Disconnect in-line vacuum harness connector. With vacuum tester, apply vacuum to port in plenum harness corresponding to suspect override position. If vacuum leaks, go to next step. If no vacuum leak is found, go to step 24) . - Check Vacuum Control Motor
Disconnect vacuum hose for vacuum motor corresponding to manual override selection where leaks were noted. Attach vacuum tester and apply vacuum. If vacuum control motor holds vacuum, replace plenum vacuum harness and retest system. If vacuum control motor leaks, replace motor and retest system. - Check Vacuum Control Motor Installation
Check attachment of vacuum control motor arm to damper door. If arm is properly attached to damper door, go to next step. If arm is not properly attached, reconnect vacuum control motor arm to damper door crank arm and retest system. - Check Damper Door Movement
Disconnect vacuum control motor. Check travel and movement of door(s) corresponding to manual override selection previously noted. If door moves smoothly through full travel, go to next step. If door does not move smoothly, repair damper door. Retest system. - Check Vacuum Motor Hoses
Connect vacuum tester to each vacuum motor hose at plenum vacuum harness port and pull vacuum. If full or partial vacuum can be pulled, hose is plugged or restricted. If hose is plugged or restricted, replace plenum vacuum harness. Retest system. If hoses are okay, go to next step. - Check Vacuum Harness Hoses
Connect in-line vacuum harness connector. Connect vacuum tester to each hose of EATC vacuum connector and try to pull vacuum. If full or partial vacuum can be pulled, hose is plugged or restricted. If hose is plugged or restricted, replace EATC vacuum harness. Retest system. If hoses are okay, go to next step. - Check EATC Assembly
Connect all vacuum motors. Reconnect EATC vacuum harness connector. Disconnect in-line vacuum harness connector. Start and run engine at idle. Connect vacuum tester to Black vacuum supply hose. Plug all other ports at plenum harness connector. Apply 15 in. Hg of vacuum. Check for vacuum leakage. If vacuum leak-down exceeds 1 in. Hg per minute, note override selection where leak occurs and go to next step. If leak-down is less than 1 in. Hg per minute, system is functioning properly. Retest system. - Leak Test Vacuum Harness
Turn ignition off. Disconnect EATC vacuum harness connector. Plug one end of hose corresponding to suspect manual override selection indicating a leak. Apply 15 in. Hg of vacuum to other end of hose. If vacuum leak occurs, repair or replace vacuum harness. Retest system. If no vacuum leak occurs, replace EATC module. Retest system.