System Testing
- Disconnect and plug air suction hose from air control valve B. Remove air cleaner cover and filter. Start engine and run at idle speed. Check for bubbling noise from air suction port. See Fig 2 .
- If bubbling noise is heard, proceed to step 6). If bubbling noise is not heard, disconnect hose No. 5 from air suction cut-off diaphragm and check for vacuum. If vacuum is present, replace air suction cut-off diaphragm and retest. If no vacuum is present, reconnect hose No. 5.
- Disconnect hose No. 15 from control box at vacuum hose manifold and check for vacuum at vacuum hose manifold. If no vacuum is present, check vacuum hose. If okay, replace air bleed valve A and retest.
- If vacuum is present, check for voltage at vacuum switch C (White/Red wire) in control box. If no voltage, check speed sensor, thermosensor and vacuum switch B (man. trans.). Check vacuum switch C. Remove control box cover.
- Check for continuity at vacuum switch C terminals with engine at idle speed. See Fig 1 . If continuity is present, replace air suction control solenoid valve and retest. If no continuity, ensure No. 20 vacuum hose is clear, replace vacuum switch C and retest.
- Heat air bleed valve A to 140°F (60°C). Ensure bubbling noise stops. If not, replace air bleed valve. Allow air bleed valve to cool before proceeding.
- Disconnect hose No. 20 from control box at vacuum hose manifold. If bubbling noise stops, system is okay. If bubbling noise is heard, disconnect hose No. 5 from air suction cut-off diaphragm and check for vacuum. If no vacuum, replace air suction cut-off diaphragm and retest.
- If there is vacuum, disconnect vacuum hose from vacuum switch C. Check for continuity between terminals of vacuum switch C. If there is continuity, replace vacuum switch C and retest. Disconnect vacuum hose No. 7 at vacuum hose manifold. Attach vacuum pump to hose.
- With engine idling, apply at least 2.4 in. Hg vacuum to hose. Bubbling noise should stop. If bubbling noise stops, system is functional and test is complete. If bubbling noise does not stop, check speed sensor, thermosensor and vacuum switch B (man. trans.). Check vacuum switch C.