Thermostatic Air Cleaner: Testing and Inspection

INTAKE AIR PREHEATING, CHECKING

Special tools, testers and auxiliary items
- VAG 1390 hand vacuum pump

Checking regulating flap
- Regulating flap vacuum unit must not be leaking
- Remove upper air cleaner housing and remove air cleaner element.





- Position upper air cleaner housing so that regulating flap in the lower air cleaner housing is visible.
- Disconnect vacuum line from temperature regulator vacuum unit.
- Connect vacuum line to VAG 1390 hand vacuum pump.
- Operate pump to apply vacuum and check freedom of movement of regulating flap and function of vacuum unit.
- Regulating flap must close off cold air intake -1-.

Checking temperature regulator
- Connect vacuum line to temperature regulator (brass connecting pipe or with notch).
- Start engine and run at idle speed.





- Check position of regulating flap after max. 20 seconds.

Temperature of temperature regulator Regulating flap position
below 20 °C (68 °F) Cold air inlet -1- closed
above 30 °C (86 °F) Warm air inlet -2- closed
Between 20° and 30 °C Between cold and warm air inlet
(68° and 86 °F)