1990 Ford Bronco II RWD, Standard, M5OD-R1FACTORY OEM SERVICE PROCEDURE

Air Control Valve (Switch-Relief)

  1. Disconnect air supply hose at inlet. Accelerate engine to 1500 RPM and verify presence of airflow in hose. Reconnect air supply hose to valve inlet.
  2. Carefully disconnect the air supply hoses at outlets "A" and "B". See Fig 1 . Carefully remove vacuum line at vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "B" with little or no airflow at outlet "A".
  3. Connect a vacuum line from manifold vacuum fitting to air control valve vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "A" with little or no airflow at outlet "B".
  4. If the conditions in steps 2 and 3 are not met, replace air control valve. If valve operates satisfactorily, restore all hose and vacuum connections.
Fig 1: Air Control Valve (Switch-Relief)
G90I14330Courtesy of FORD MOTOR CO.
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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