A3 Mk2
| Incorporation of auxiliary heater on vehicles without heater coolant shut-off valve -N279- |
Note| Currently all models and engine versions are fitted with a heater coolant shut-off valve -N279- (discontinuation of heater coolant shut-off valve -N279- not yet finalised) → Engine, mechanics; Rep. Gr. 19. |
| Direction of coolant flow |
| -⇒- With engine running and in auxiliary heating mode |
| 1 - | Auxiliary heater |
| 2 - | Circulation pump -V55- |
| q | Circulation pump -V55- is activated by auxiliary heater control unit -J364- |
| q | Under certain conditions, the circulation pump may also be activated when the engine is running to assist the coolant pump of the engine → Guided Fault Finding function of vehicle diagnostic, testing and information system VAS 5051. |
| q | Checking → Guided Fault Finding function of vehicle diagnostic, testing and information system VAS 5051 |
| q | Removing and installing → Chapter |
| 3 - | Heat exchanger of air conditioning unit |
| 4 - | Non-return valve |
| q | Not fitted with all engine versions → Engine, mechanics; Rep. Gr. 19; Cooling system |
| q | Not visible from outside, fitted in coolant hose (bleeder hose) → Chapter and → Electronic parts catalogue |
| q | Non-return valve remains closed in auxiliary heating mode (pressure generated by circulation pump is not sufficient to open valve). |
| q | With engine running, coolant circuit is bled by way of this non-return valve. |
| 5 - | Forced ventilation of coolant circuit |
| q | Incorporation into engine coolant circuit → Engine, mechanics; Rep. Gr. 19; Cooling system |
| 6 - | Non-return valve |
| q | Not fitted with all engine versions → Engine, mechanics; Rep. Gr. 19; Cooling system |
| q | Not always visible from outside, may be fitted in coolant hose → Chapter and → Electronic parts catalogue |
| 7 - | Coolant supply from engine |
| q | Incorporation into engine coolant circuit → Engine, mechanics; Rep. Gr. 19; Cooling system |
| 8 - | Coolant return to engine |
| q | Incorporation into engine coolant circuit → Engine, mechanics; Rep. Gr. 19; Cooling system |
