Help with air filter problems (Opel Vectra B)

Preheating of intake air

Functional testing with auxiliary means

To check the intake air preheating, disconnect the vacuum line to the control flap on the thermostatic valve.

Suck air through this pipe - the warm air damper should close or, without reduced pressure, open again.

If not, check the pipeline for leaks and also check whether the valve moves easily.

Put the hose back on.