This system consists of an adjustable damper bypass mounted on the air cleaner intake nozzle to control the ratio of cold to warm air flowing into the carburetor. The damper position of the device is changed using a vacuum diaphragm, which, in turn, is subjected to force from a temperature-sensitive element located inside the air filter.
The system has a huge impact on the traction qualities of the engine and the toxicity of exhaust gases precisely during the first kilometers of a car with a cold engine.
On a cold engine, the damper of the device completely blocks the channel of the air filter intake pipe, while only warm air enters the carburetor, which previously flows around the exhaust manifold. As the engine warms up, the damper opens slightly and an increasing amount of cold air begins to flow through the intake pipe. When the engine is fully warmed up, the damper opens completely, providing full access to fresh cold air.
The automatic air temperature control system is only designed to supply warm air on a cold engine, so it is important to check it periodically to prevent the engine from malfunctioning after warming up due to the supply of a cold or overheated air-fuel mixture.
If the air filter flap sticks to the position «no heat», then the engine idles unsteadily and stops before it is fully warmed up, as a result of which it is necessary to additionally press the accelerator pedal. When the damper sticks in the position «heat» due to the constant supply of hot air to the carburetor, it will give the impression that the engine is out of adjustment.
Checking the technical condition
Checking the technical condition and maintenance is given in sec. 2. If it becomes necessary to check during routine maintenance, proceed in accordance with the sequence below.
If the air temperature control damper does not completely cut off the cold air supply after starting a cold engine, disconnect the hose from the vacuum diaphragm on the intake pipe and place your thumb on the hose opening. If there is a vacuum applied to the diaphragm, then the cause of this may be freezing or gluing of the damper and thrust inside the air filter intake pipe. If there is a vacuum pump, apply a vacuum to the damper actuator to make sure it works by first disconnecting the standard vacuum hose. If vacuum from the pump does not open the temperature regulator flap, and if the vacuum hose is properly connected, the flap opens freely, replace the vacuum diaphragm.
If there is no diaphragm vacuum in the above test, check the hoses for cracks, kinks, and tight connections.
If the hoses are not clogged and in good condition, replace the temperature sensor located inside the air filter housing.
Replacement Parts
Air Filter Vacuum Diaphragm
Disconnect the vacuum hose from the diaphragm.
Remove the restrictor screw, unhook the rod and unscrew the diaphragm from the air filter housing.
When installing, insert the diaphragm into the air filter housing, screw it in, attach the rod, screw in the limiter screw.
Connect the vacuum hose.
Air filter temperature sensing element
Remove the air filter to gain access to the space underneath.
Note the location of the vacuum hoses and disconnect them from the temperature sensor.
Carefully mark the position of the element, as this is exactly the position where the new element should be installed. Lift the element out of the air filter housing.
Install the new element exactly in the same position as the removed one, attach the vacuum hoses.
Install the filter element and filter top cover.