DESCRIPTION
The automatic temperature controlled air cleaner is designed so that the temperature of air drawn into the carburetor is automatically controlled. This helps maintain a constant air/fuel ratio for more efficient fuel combustion.
The system consists of a thermo-sensor, a vacuum motor, a hot air control valve, a hot idle compensator, and connecting hoses. All components are mounted to the air cleaner body.
OPERATION
When air cleaner is cold, vacuum motor diaphragm is pulled by intake manifold vacuum and opens the hot air control valve. This allows intake of hot air from heat stove on exhaust manifold.
When air cleaner reaches a temperature of 100-111°F (38-44°C), thermo-sensor comes into function and stops supply of vacuum from intake manifold. When vacuum is stopped, hot air control valve opens and permits entry of cool outside air. This holds temperature of intake air at a nearly constant temperature.
HOT IDLE COMPENSATOR
The air/fuel mixture tends to richen when engine is running at idle during periods of high operating temperatures. To offset this rich mixture, a hot idle compensator feeds cool ambient air into intake manifold to lean the temporarily rich air/fuel mixture.
MAINTENANCE
The thermostatic air cleaner and hot idle compensator should be inspected every 60,000 miles for proper operation. Replace air cleaner element every 30,000 miles.
Thermostatic Air Cleaner Vacuum Diagram. Scheme 11
VACUUM MOTOR & HOT AIR CONTROL VALVE
- Connect vacuum motor directly to intake manifold vacuum source. With vacuum at zero, look through air cleaner snorkel and make sure hot air control valve is completely closed.
- Start engine and allow to idle. Hot air control valve should open immediately, closing fresh air side of snorkel. If valve does not operate smoothly, check for binding.
THERMO-SENSOR
- Remove air cleaner cover and place a thermocouple type thermometer on thermo-sensor. Replace air cleaner cover.
- With thermo-sensor cool, start engine and check that hot air control valve is closed to outside air. When valve begins to move, read thermometer. It should read 100-111°F (38-44°C). If not, replace thermo-sensor.
With thermometer installed in air cleaner housing, run engine at idle with air cleaner cover removed. Hot idle compensator should begin to open at 115-126°F (46-52°C). If not, replace hot idle compensator.