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Home >> Ford >> 1978 >> Fiesta >> Repair and Diagnosis >> Engine Mechanical >> Auxiliary Emission Control Systems >> THERMACTOR I System >> Operation >> Cold Engine Lock-Out/Overheat Protection (1975-76 Models) >> System 2: Normally Closed

System 2: Normally Closed

  1. When engine is operating at normal temperature, solenoid vacuum valve does not operate. This will allow vacuum through the VDV and thermactor will direct air to exhaust system.
  2. If normally open switch(s) closes (due to cold air temperature or overheated floor pan), solenoid vacuum valve will operate. When solenoid vacuum valve operates on this system, this causes VDV to operate by-pass valve and dump thermactor air to atmosphere.
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