Operation of and removing/installing heater coolant shut-off valve N279 — AUDI

Operation of and removing/installing
heater coolant shut-off valve
N279
Note
Currently only fitted on vehicles with
“Auxiliary heater”
optional extra.
Not fitted on vehicles with diesel engine on which the auxiliary/supplementary heater is only used as supplementary heater (vehicles without
“Auxiliary heater”
optional extra)
Chapter
.
The
heater coolant shut-off valve
N279
is currently actuated throughout the entire auxiliary heating phase irrespective of the coolant temperature (the coolant flows in the small circuit, the engine is not pre-heated).
In auxiliary heating mode, the
heater coolant shut-off valve
N279
is actuated by the
supplementary heater control unit
J364
until the coolant temperature in the auxiliary heater has reached a specified level (this function is not available at present, introduction not yet finalised)
"Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051
and
Chapter
.
The display in the measured value block for actuation of the
heater coolant shut-off valve
N279
differs and depends on the vehicle model and the version of the
supplementary heater control unit
J364
. On the Audi Q7 at present for example, a display of 100 % indicates that 100 % of the coolant is being conveyed in the large circuit and that the
heater coolant shut-off valve
N279
is not being actuated
Vehicle diagnostic, testing and information system
VAS 5051 A
, "Guided fault-finding" function.
As of Model Year 2014, vehicles with certain engines with no
“auxiliary heater”
as optional extra will be fitted with a
coolant shut-off valve
N82
Heating, air conditioning
Rep. gr.
87
.
N82
is actuated by the front operating and display unit,
Climatronic control unit
J255
if passenger compartment heating is not required
Current flow diagrams, Electrical fault finding and Fitting locations
and
"Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051
.
On vehicles with an
“auxiliary heater”
as optional extra and an engine which is really intended to have
N82
, the
heater coolant shut-off valve
N279
is actuated by the
supplementary heater control unit
J364
when requested by
J255
(pay attention to auxiliary heater adaption)
"Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051
Operation
If voltage is not applied to the
heater coolant shut-off valve
N279
(large coolant circuit), the coolant can flow from connection
A
(from the heat exchanger in the front air conditioning unit) to connection
C
(to the engine).
If voltage is applied to the
heater coolant shut-off valve
N279
(small coolant circuit), the coolant can flow from connection
A
(from the heat exchanger in the front air conditioning unit) to connection
B
(to the
coolant circulation pump
V50
).
Removing
Remove the auxiliary/supplementary heater
Chapter
.
Unfasten the clamps
A
.
Unplug the connector
C
.
Screw out the bolts
B
of the
heater coolant shut-off valve
N279
.
Remove the
heater coolant shut-off valve
N279
.
Installing
Install in reverse order, paying attention to the following:
If applicable, check actuation and operation of the
heater coolant shut-off valve
N279
"Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.