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Thermostatic Air Cleaner (THERMAC): Testing

  1. Ensure heat tube is fitted to heated air inlet, and damper door in air cleaner has freedom of movement See Fig 1 . Ensure damper door spring is attached, and is pulling door against wax-pellet actuator. Ensure air cleaner-to-TBI seal is in place.
  2. Ensure damper door is open to heated air inlet when engine is not running and temperature is cold. Observing damper door through cold air inlet, start engine and ensure damper door is closed to outside cold air.
  3. As engine warms over a period of several minutes, damper door should open slowly to outside air. If door does not open slowly, replace wax-pellet actuator or filter assembly.
Fig 1: THERMAC System Component ID
G121795Courtesy of GENERAL MOTORS CORP.