Audi Q7 2007 Repair Manual page 238

Audi Q7 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 04.2013
Check the functionality of the Coolant Recirculation Pump - V50- ,
the Water Pump - V36- , the Coolant Shut-Off Valve - N82- and
the Auxiliary Heater Heating Element - Z35- .
Note
From MY 2009, certain vehicles with a 6-cylinder TDI engine
♦
without an "auxiliary heater", have an Auxiliary Heater Heating
Element - Z35- instead of a fuel-driven auxiliary heater instal‐
led depending on the emissions standard (running change
depending on the engine). Refer to
⇒ "9.19 Auxiliary Heater Heating Element Z35 , Removing and
Installing", page 140
Diesel vehicles without a fuel-driven auxiliary heater (or the
♦
optional equipment "parking heater") have an Auxiliary Heater
Heating Element - Z35- near the heat exchanger. The air leav‐
ing the heat exchanger in the front of the A/C unit is also
heated by the Auxiliary Heater Heating Element - Z35- .
Auxiliary Heater Heating Element - Z35- . For removing and
♦
installing, refer to
⇒ "9.19 Auxiliary Heater Heating Element Z35 , Removing and
Installing", page 140
⇒ "8.4 Auxiliary Heater Heating Element Z35 , Checking",
page 85 .
If coolant circuit is not completely bled after filling, air may ac‐
♦
cumulate in heater cores of A/C units or A/C units, thus re‐
ducing heating performance of A/C system, additional noises
may occur or customer may complain of different air temper‐
atures flowing out of vents at driver's side and front passeng‐
er's side at the same setting. Bleed coolant circuit, if
necessary. Refer to
Depending on engine, coolant circulation for the A/C system
♦
is ensured by various pumps or these pumps support the en‐
gine coolant pump with engine running. Vehicles with an 8-
cylinder engine, a 6-cylinder TDI engine and a 12-cylinder TDI
engine have a Coolant Recirculation Pump - V50- . 6-cylinder
gasoline vehicles has a Water Pump - V36- . A 6-cylinder gas‐
oline vehicle with a parking heater as an optional equipment
has both a Water Pump - V36- and a Coolant Recirculation
Pump - V50- . Refer to
⇒ "6 Incorporation of the A/C System in Vehicle Coolant Cir‐
cuit", page 66 .
If customer complains of poor heating performance at specific
♦
engine speeds, check incorporation of A/C system in the cool‐
ant circuit. If both coolant hoses (supply and return) from
engine via the Coolant Recirculation Pump - V50- ( Water
Pump - V36- ) to heater core is interchanged, the engine cool‐
ant pump works against the Coolant Recirculation Pump -
V50- ( Water Pump - V36- ) and coolant no longer flows into
heater core(s) at certain engine speeds. Refer to
⇒ "6 Incorporation of the A/C System in Vehicle Coolant Cir‐
cuit", page 66 , XXXXX ⇒ Parking/Auxiliary Heater; Rep. Gr.
82 and ⇒ Engine Mechanical; Rep. Gr. 19 .
232
Rep. Gr.87 - Air Conditioning
.
; for checking, refer to
⇒ "7 Coolant Circuit, Bleeding", page 78 .
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with respect to the correctness of information in this document. Copyright by AUDI AG.