audi Workshop Repair Guides

Audi Workshop Service and Repair Manuals

ABOUT US
Diverting fuel for auxiliary heater > < Rules for cleanliness when working on auxiliary heater (and fuel system)

A5

Bleeding coolant circuit
Bleeding coolant circuit
Special tools and workshop equipment required
   
t  Cooling system filler unit -VAS 6096-
  Note
t  The auxiliary heater removal and installation methods described in this Workshop Manual ensure that only a small quantity of air ingresses into or remains in the coolant circuit. Full bleeding of the coolant circuit is thus not necessary after removing and installing the auxiliary heater.
t  If, however, a large quantity of coolant has escaped on account of some other problem, e.g. a leaking hose, or following the replacement of coolant pipes, the coolant circuit is to be completely bled using the Cooling system filler unit -VAS 6096- → Engine, mechanics; Rep. Gr.19.
t  After bleeding and filling the coolant circuit with the cooling system filler unit -VAS 6096-, the auxiliary heater and the circulation pump -V55- are to be bled as described below → .
Bleeding auxiliary heater coolant circuit
  Note
t  The following illustration shows the position of the auxiliary heater on an Audi A5 Coupé. The layout differs slightly on the Audi A4 and Audi Q5. On these other vehicles the work is however to be performed in the same manner as described for the Audi A5 Coupé.
t  The circulation pump -V55- must be completely filled with coolant to prevent the pump being destroyed by dry running.
  W00-1269
t  As only a small quantity of coolant escapes from the coolant circuit when removing and installing the auxiliary heater and only a small quantity of air remains in the coolant circuit on installation → Chapter (the auxiliary heater and circulation pump -V55- are already filled with coolant on installation), there is no further need for extensive bleeding.
t  After removing the hose clamps -2- and -3-, actuate the circulation pump -V55- if necessary by way of the final control diagnosis routine → Vehicle diagnostic, testing and information systemVAS 5051/, “Guided fault-finding function”. This additionally bleeds the coolant return from the heat exchanger in the air conditioner unit via the heater coolant shut-off valve -N279- to the circulation pump -V55- → Chapter.
Requirement
Most of the coolant circuit is filled with coolant; there are only a few air bubbles at a few locations in the coolant circuit.
–  Fill the coolant expansion tank with coolant as far as the upper mark.
–  Switch on ignition.
–  Set the temperature on the operating and display unit, Climatronic control unit -J255- to “HI” (for the driver's and front passenger's side).
–  Switch on the “auxiliary heater” by way of the “AC” function in the “Car” menu of the MMI (Multi Media Interface) → Infotainment / MMI operating instructions or e.g. via the vehicle diagnostic, testing and information system, “Basic setting” function → Vehicle diagnostic, testing and information systemVAS 5051/, “Guided fault-finding function”.
–  Allow the auxiliary heater to run for at least 2 minutes in full load mode (the circulation pump -V55- starts up and the heater coolant shut-off valve -N279- is actuated).
–  Start the engine and set the temperature on the operating and display unit, Climatronic control unit -J255- to “HI” (for the driver's and front passenger's side).
–  Run the engine for at least 2 minutes at high idle (approx. 2000 to 2500 rpm).
–  Switch off the engine and the auxiliary heater.
  WARNING
The cooling system is pressurised. When the engine is warm, the coolant temperature may be in excess of 90 °C. Dissipate pressure and allow to cool down before performing repairs. Dissipate the pressure in the coolant circuit by opening the cap at the coolant expansion tank → Engine, mechanics; Rep. Gr.19.
–  Check the coolant level in the coolant expansion tank and replenish the coolant if necessary → Engine, mechanics; Rep. Gr.19.
  A82-10115

Diverting fuel for auxiliary heater > < Rules for cleanliness when working on auxiliary heater (and fuel system)