Combination Air By-Pass/Air Control Valve
- Disconnect hoses from outlets "A" and "B". See Fig 1
. Disconnect and plug vacuum line to port "D". With engine operating at 1500 RPM, airflow should be flowing from by-pass vents.
- Reconnect vacuum line to port "D". Disconnect and plug vacuum line to port "S". Ensure vacuum is present in line to vacuum port "D". Accelerate engine to 1500 RPM. Airflow should be noted coming out of outlet "B". No airflow should be detected at outlet "A".
- Apply 8-10 in. Hg vacuum to port "S". With engine operating at 1500 RPM, airflow should be noted coming out of outlet "A". If valve is bleed type, less air will flow from outlet "A" or "B" and main discharge will change when vacuum is applied to port "S".
- If conditions in previous steps are not met, replace valve. If conditions are met, valve is okay. Reconnect hoses and vacuum lines.
Courtesy of FORD MOTOR CO.