Air Cleaner - Thermostatic Ford Mustang III рестайлинг

DESCRIPTION

During cold engine operation most passenger cars preheat the air entering the carburetor or the fuel injection unit. This system maintains incoming air temperature to a point where the carburetor or fuel injection system can be kept lean to reduce hydrocarbon (HC) emissions, and reduce carburetor icing.

Most passenger cars are equipped with dry type air cleaners with a replaceable air filter element. These air inlet systems have various sensors, switches and vacuum motors to control inlet air temperature. There are also various sensors present in the air cleaner for other engine control systems.

Scheme 21

OPERATION

Most systems regulate the air inlet temperature by using air from a cool air source as well as heated air from a heat shroud which is mounted on the exhaust manifold. The duct and valve that regulates the airflow from these two sources is located inside the air cleaner, on the outside of air cleaner or remotely mounted in one of the inlet tubes. Airflow is regulated by a vacuum motor operated door. Motor operation is controlled by delay valves, temperature sensors and other vacuum controlled systems, depending upon vehicle application.

The air control door temperature sensor closes when the temperature of air entering the air cleaner is less than the calibration of the temperature sensor. This allows engine vacuum to operate the air control door vacuum motor, and warm manifold air to be routed to the intake. (Scheme 22)

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

As air inside the air cleaner warms, the temperature sensor begins to open, bleeding off vacuum to the vacuum motor. As vacuum to vacuum motor decreases, the 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, the air control door opens completely, and closes off the intake of heated air.

VACUUM CONTROL TEMPERATURE SENSOR

The vacuum control temperature sensor controls the operation of the air control door. During initial start-up situations, this valve directs engine vacuum to the air control vacuum motor. The motor closes the air intake door, allowing the intake of heated manifold air. When the intake air temperature reaches a precalibrated value, this valve opens, allowing the intake of cooler outside air.

Scheme 22

VACUUM OPERATED DUCT TEST

The purpose of the duct system is to provide warm air from the heat shroud to the air intake system. When vehicle is warm it maintains a temperature between 70°F (21°C) and 105°F (40°C) by mixing warm and cool air. Surrounding air temperature should be above 60°F (15°C) when testing system operation.

1. Block wheels and apply parking brake. Inspect heat riser tube, repair or replace as necessary. Remove components required to observe operation of duct door. Door should be open to fresh air at this time. Check for sticking or binding, repair as necessary.
2. Check vacuum source and condition of vacuum hoses at bimetal sensor, Cold Weather Modulator (CWM) and vacuum motor. Start engine. If door closes to fresh air (open to heated air from manifold), go on to step 3). If not, place finger over bleed hole in bimetal sensor. Duct door should quickly close to fresh air (open to manifold heated air). If not, replace vacuum motor and retest.
3. If vehicle is equipped with a delay valve before vacuum motor, replace with straight through vacuum hose for this test. With engine off, cool bimetal sensor and CWM with refrigerant for 20 seconds. CAUTION: Do not cool sensor with refrigerant while engine is running. If drawn into intake system, poisonous phosgene gas will be exhausted into work area. Perform test in well ventilated area.
4. Restart engine. Door should fully close to fresh air (open to manifold heated air). If not, replace sensor. Stop engine, cool CWM and sensor. Restart and run engine briefly (under 15 seconds). Door should close to fresh air (open to manifold heated air). See the AIR CONTROL DOOR CLOSING VACUUM table.
5. Shut off engine and observe door. On vehicles without CWM, the door will slowly open to fresh air (closed to manifold heated air) in 10 to 30 seconds. Vehicles with CWM, the door should not open to fresh air (closed to manifold heated air) for at least 2 minutes. If less replace CWM. Cool CWM and sensor, then retest.

AIR CONTROL DOOR CLOSING VACUUM

COLD WEATHER MODULATOR

Using a vacuum pump with gauge, apply 16 in. Hg of vacuum to motor side of modulator. Determine if modulator holds or leaks within the correct temperature range. See COLD WEATHER MODULATOR SPECIFICATIONS table.

COLD WEATHER MODULATOR SPECIFICATIONS