2. This check is a simple inspection. If access is limited, you will have to use a small mirror.
3. Open the hood and locate the spring loaded flap inside the air filter assembly. It is located inside the metal casing of the air filter, which is shaped like a pipe. Make sure the flexible air hose (hoses) attached securely and not damaged.
4. If there is a flexible air duct attached to the end of the filter housing that goes to the grille, disconnect it from the housing - this will allow you to see the spring-loaded flap inside the filter assembly.
5. Checking is carried out in cool weather and with a cold engine. When starting the engine, the spring-loaded filter flap should close. When the damper is closed, air cannot enter the filter through the end of the casing, so air is drawn into it through a flexible channel going to the exhaust manifold.
6. As soon as the engine warms up to operating temperature, the filter flap should open. Depending on the ambient temperature, warming up can last 10-15 minutes. To speed things up, you can connect an air duct to the end of the filter housing and take a short trip and then check if the filter flap is fully open (photo).
The spring-loaded filter flap is visible after the air duct has been removed
7. If the thermostatic air filter is not working properly, see Section 6.