Examination
1. The operation of the thermostat is checked visually using a mirror.
2. Locate the thermostat shutter.
3. On some vehicles, disconnect the cold air duct from the filter socket in the direction of the arrow (1). damper (2) should be visible through the bell.
4. When the engine warms up, the damper should gradually close the filter socket, to which the hose from the exhaust manifold and preheater is connected.
5. After the engine warms up, the damper (1) must open the cold air duct completely (see subsection 6.5).