Coolant Circuit, Bleeding; A/C System Coolant Circuit Section, Bleeding - Audi Q7 2007 Repair Manual

Audi Q7 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 04.2013
7

Coolant Circuit, Bleeding

⇒ "7.1 A/C System Coolant Circuit Section, Bleeding",
page 78
7.1 A/C System Coolant Circuit Section,
Bleeding
Note
The removal of A/C system components (except for compres‐
♦
sor in vehicles with 8-cylinder FSI engine) is described in this
repair manual in such a way that only a small amount of air
enters the cooling circuit, therefore it is not necessary to bleed
cooling circuit completely after removing and installing these
components.
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If, however, a large amount of coolant flows out due to a dif‐
♦
ferent complaint, for example due to a leaking hose, compres‐
sor replacement on vehicles with 8-cylinder FSI engine or after
coolant hose replacement, the cooling circuit is to be bled
completely using the Cooling System Charge Unit -
VAS6096- . Refer to ⇒ Engine Mechanical; Rep. Gr. 19 ;
Coolant System .
After bleeding and charging the cooling circuit with the Cooling
♦
System Charge Unit - VAS6096- , the section of the cooling
circuit with the A/C system (heater core and associated hoses)
is to be post-bled as described below.
Prerequisite
– The cooling circuit is essentially filled with coolant, there are
only a few air bubbles in only a few locations of the cooling
circuit.
Note
Since it was pre-filled when installing A/C system components
♦
(such as the heater core), only a small amount of air is in the
cooling circuit, therefore it is sufficient to set the A/C system
to maximum heat output when engine is warm (so that recir‐
culation pump is actuated) and to let engine run for a few
minutes at increased idle speed (approximately 2000 RPM) in
order to bleed the cooling circuit completely.
When bleeding coolant circuit, take special care to ensure
♦
complete bleeding of heat exchangers. If air bubbles remain
in heater cores, there may be complaints made by customers
about insufficient heating performance in the winter, or differ‐
ent air temperature from the vents at the same setting in
regulated mode. Refer to
⇒ "14 Heating Performance of A/C System, Checking",
page 231 .
Bleeding
– Fill coolant into coolant expansion tank up to top marking. Re‐
fer to ⇒ Engine Mechanical; Rep. Gr. 19 ; Coolant System .
– Start engine and let it run until it reaches operating tempera‐
ture.
– Set the Climatronic control module - J255- front A/C display
control head (and the Rear A/C Display Control Head - E265- ,
if present) to maximum heat output (for example, temperature
78
Rep. Gr.87 - Air Conditioning