Intake Air Control System

Thermostatic Air Cleaner (THERMAC)

A heated air system is used to provide good driveability under varying climatic conditions. By having a uniform inlet air temperature, the fuel system can be calibrated to reduce exhaust emissions.

The THERMAC is operated by a heated air and wax pellet actuator similar to the one that operates the engine thermostat. When the temperature is less than 85°F (30°C), the wax pellet contracts and the damper door will shut off the outside air. This allows heated air from around the exhaust manifold to enter the air cleaner.

When temperature is greater than 130°F (55°C), the damper door allows only outside air to enter the air cleaner. When temperature is 85-130°F (30-55°C), the damper door allows both heated and outside air to enter the air cleaner.