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Normally Closed Valve

  1. With engine idling at normal operating temperature and ambient air above 65°F (18°C), disconnect vacuum hose to thermactor air by-pass valve. If air dumps to atmosphere through exhaust ports in silencer cover, hose connections are correct. Reconnect vacuum hose.
  2. Disconnect vacuum supply hose from bottom fitting of solenoid valve and check for manifold vacuum. If no vacuum, check and/or replace vacuum source hose as required. Reconnect vacuum hose. (Vacuum supply ALWAYS goes to bottom fitting on solenoid vacuum valve.)
  3. Disconnect wires to solenoid vacuum valve and determine which wire has B+ voltage with ignition switch in RUN position. Connect B+ wire to solenoid vacuum valve. With engine idling, ground other exposed terminal on valve. Air should NOT dump to atmosphere.
  4. Connect wires as originally installed and note that thermactor air is NOT being dumped to atmosphere. Replace solenoid valve if air dumps in either solenoid test.
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