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Home >> Ford >> 1983 >> EXP Base, 1.6 4, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> THERMACTOR System >> Testing >> Air Bypass/Air Control Valve >> Normally Closed Valve
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Normally Closed Valve

  1. With engine at normal operating temperature, parking brake applied and transmission in "P" or "N," disconnect hoses from ports "A" and "B." See Figure Disconnect and plug line to port "D." With engine at 1500 RPM, air should flow from bypass vents.
  2. Reconnect line to port "D" and disconnect and plug line to port "S". Ensure vacuum is present in line to port "D." With engine at 1500 RPM, air should flow from port "B," and no air should flow from port "A".
  3. Apply 8-10 in. Hg vacuum to port "S." With engine at 1500 RPM, air should flow from port "A." If the valve has a vacuum bleed, some lesser amount of air will flow from port "A" or "B" and main discharge will change when vacuum is applied to port "S".
  4. If valve fails any test, replace valve. Reconnect hoses.
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