Air Cleaner - Thermostatic Dodge Aries I

DESCRIPTION

All passenger cars are equipped with a system for preheating the air entering the carburetor or fuel injection unit.

This device maintains incoming air temperature at a point where the carburetor or fuel injection unit can be calibrated much leaner to reduce hydrocarbon (HC) emissions. It also improves warm-up operations and reduces carburetor icing.

This system consists of an air cleaner assembly, integral air control door, vacuum control temperature sensor, vacuum motor, heat shroud (on exhaust manifold), heated air tube and vacuum hoses.

Some models also use additional controls such as vacuum traps, cold weather modulators, vacuum check valves and vacuum delay valves.

Exploded View of Thermostatic Air Cleaner Assembly. Scheme 16

OPERATION

When temperature of air entering air cleaner is less than calibrated temperature of temperature sensor, sensor closes. This allows engine vacuum to operate vacuum motor.

When engine vacuum is applied to vacuum motor, door closes off outside air. Air is then drawn into air cleaner from around exhaust manifold.

As air inside air cleaner warms, temperature sensor begins to open. This gradually bleeds off vacuum to vacuum motor. As vacuum to vacuum motor decreases, air control door begins to open.

As air control door opens, outside air is allowed to enter air cleaner assembly. When air entering air cleaner reaches a predetermined temperature, air control door opens completely. This completely closes off air from around exhaust manifold.

Thermostatic Air Cleaner Assembly with Temperature Sensor & Vacuum Motor. Scheme 17

VACUUM CHECK VALVE & DELAY VALVE

A vacuum check valve and/or delay valve is used on thermostatic air cleaner. During cold weather operation, and when engine is under full or hard acceleration, valve will postpone opening of air control door to outside air. Engine will continue to receive heated air for a short period of time to improve driveability.

Thermostatic Air Cleaner Assembly Showing Air Flow into Carburetor. Scheme 18

TESTING

Note. See SPECIFICATIONS tables for correct specifications when performing following tests.

VACUUM CONTROL TEMPERATURE SENSOR

1. Tape a thermometer close to vacuum control temperature sensor located inside air cleaner. Leave wing nuts off top of air cleaner so that top can be quickly removed to read thermometer during test.
2. With engine cold, temperature below vacuum control temperature sensor specifications, check air control door in air cleaner. It should be in fully open position (open to outside air).
3. Start engine. As soon as engine starts, door should move to full heated air position (closed to outside air). Watch air control door. When door reaches fully open position, quickly remove air cleaner top and read thermometer.
4. Compare thermometer reading with specifications. If reading is not to specifications, perform vacuum motor test. If vacuum motor is okay, replace sensor.

VACUUM CONTROL TEMPERATURE SENSOR SPECIFICATIONS

VACUUM MOTOR TEST

1. Remove air cleaner from vehicle. Disconnect vacuum hose from vacuum motor. Apply 20 in. Hg vacuum to motor and pinch off hose. Vacuum should not leak down more than 10 in. Hg in 5 minutes. If vacuum motor does leak down, replace it.
2. Connect a vacuum pump to vacuum motor. Apply specified amount of vacuum to vacuum motor to open or close heated air door. If door does not open or close at specified vacuum, replace vacuum motor.

AIR CONTROL DOOR OPERATING VACUUM