Audi Q7: Cooling Output, Checking
Special tools and workshop equipment
required
- Vehicle Diagnostic Tester with the "Guided Fault Finding"
function and the corresponding connection lines. Refer to
Workshop Equipment.
- A standard thermometer (for temperature measurement; if
necessary, a thermometer with two measuring probes for
simultaneous measurement, for example, for temperature on the
right and left).
- The cooling output test requirements are met. Refer to
→ Chapter "A/C Cooling Output, Testing Requirements".
- Measure the ambient temperature (must be warmer than 15 ºC
(59 ºF) ).
- Close the doors, the engine hood, the windows, the sliding
sunroof and the rear lid.
- Open all instrument panel vents, the B-pillar vents, and the
vents in the rear center console.
- Start the engine.
- Switch off the A/C compressor ("ECON" mode set on the Front
A/C Display Control Head -E87- the indicator lamp in the
A/C and the A/C
MAX buttons do not turn on).
- Initiate the A/C system Guided Fault Finding. Refer to
Vehicle Diagnostic Tester.
- Select the measured values for the activation of the A/C
compressor and the pressure in the coolant circuit and read out
the measured values in the "read measured values" function.
Refer to Vehicle Diagnostic Tester in the "Guided Fault Finding"
function.
Note
For the following test, various measured values can be
selected in Guided Fault Finding and displayed in a table. Refer
to Vehicle Diagnostic Tester in the "Guided Fault Finding"
function.
For the cooling output test, it is helpful to display the
following measured values of the Front A/C Display Control Head
-E87-:
Note
Depending on vehicle equipment, there are different versions
of the A/C system for the Audi Q7. Make sure to use the correct
version and pay attention to the allocation of different
components. Refer to
→ Chapter "A/C System Versions" and Parts Catalog.
- The measured values of the following temperature sensors
(Evaporator Vent Temperature Sensor -G263-, Left Front Upper
Body Vent Temperature Sensor -G385-, Right Front Upper Body Vent
Temperature Sensor -G386-, Left Footwell Vent Temperature Sensor
-G261-, Right Footwell Vent Temperature Sensor -G262-).
- The measured value of the Rear Upper Body Vent Temperature
Sensor -G537- (only installed for a vehicle with a "Low"Mid" or
"Mix" A/C system, a rear air distribution housing, without and
with a Rear A/C Display Control Head -E265- version
-A-).
- The request or the activation of the following components
(Fresh Air Blower -V2-, Rear Fresh Air Blower -V80-, Radiator
Fan -V7-, Radiator Fan 2 -V177-).
- The request or the activation of the following components
(if equipped, depending on the equipment and engine type Coolant
Recirculation Pump -V50-/Recirculation Pump -V55-, Coolant
Shut-Off Valve -N82-/Heater Coolant Shut-Off Valve -N279-).
- The request or activation of the A/C Compressor Regulator
Valve -N280- (compressor shut-off conditions and actual
compressor current)
- The coolant temperature and the ambient temperature.
- The measured value for the High Pressure Sensor -G65-
(refrigerant pressure).
Checking
- The A/C compressor is switched off. A current of 0 A (amps)
for the activation of the A/C Compressor Regulator Valve -N280-
is displayed.
- The refrigerant circuit pressure is same at the measured
ambient temperature or is greater than the value in the table.
Note
- At absolute pressure, 0 bar corresponds to absolute vacuum.
Normal ambient pressure equals approximately 1 bar (14.5 psi)
absolute pressure and 0 bar pressure. On the scales of most
pressure gauges, 0 bar pressure corresponds to an absolute
pressure of one bar (can be seen from -1 mark below 0).
- Depending on the version of the Front A/C Display Control
Head -E87-, only integer values may be displayed as measured
values. If the measured pressure is between two values, the
display alternates between the two values.
- Pressure in refrigerant circuit is governed by the ambient
temperature. On account of heat given off by components (for
example, the radiator), pressure displayed with warm engine will
be slightly higher than that given for the respective ambient
temperature.
- If pressure displayed is below that indicated in table.
Check the signal of the High Pressure Sensor -G65-. Refer to
Vehicle Diagnostic Tester in the "Guided Fault Finding"
function. If no fault can be determined at the High Pressure
Sensor -G65-, there is insufficient refrigerant in the circuit.
Bring the vehicle to a workshop that has the necessary tools and
where the work can be performed accordingly by qualified
personnel. Refer to
→ Refrigerant R134a Servicing; Rep. Gr.87; A/C System, General
Information.
The Refrigerant Circuit Pressure is OK
- Switch the A/C compressor on by selecting the "Auto" mode on
the Front A/C Display Control Head -E87- front A/C display
control head (the indicator lamps in the
AUTO buttons and the A/C MAX
button illuminates).
Note
By selecting the SYNC function on
the Front A/C Display Control Head -E87- on vehicles with a
"High" A/C system the settings of the front driver side are
transferred to the front passenger side and also the Version
-B-Rear A/C Display Control Head
-E265-.
- Via the rotary switch(es) of the Front A/C Display Control
Head -E87-, the temperature preselection is set to "cold" (for
the driver and front passenger side).
- On vehicles with a "Mid" or "Mix" A/C system on the Rear A/C
Display Control Head -E265- adjust the temperature preset for
the rear to "cold".
- On vehicles with a "High" A/C system on the Rear A/C Display
Control Head -E265- adjust the temperature preset for the left
and right rear side to "cold".
- Via the rotary switches or buttons on the Front A/C Display
Control Head -E87-, set the air flow direction to the
"instrument panel vents" (for the driver and front passenger
side).
- In vehicles with a "High" A/C system on the Rear A/C Display
Control Head -E265-, set the air flow direction via the rotary
switches on the Rear A/C Display Control Head -E265- (version
-B-) to the vents in the rear
center console.
Note
- The indicator lamp in the AUTO
button goes out when performing manual changes for the airflow
direction and/or the fresh air blower speed.
- The maximum possible fresh air blower speed depends on
several conditions (coolant temperature, vehicle voltage, etc.)
- In the "read measured values" for the Front A/C Display
Control Head -E87-, read the actual current with which the A/C
Compressor Regulator Valve -N280- is activated (if the actual
current is greater than 0.3 A, then the A/C compressor is
switched on). Refer to Vehicle Diagnostic Tester in the "Guided
Fault Finding" function.
Note
- The target current is calculated by the Front A/C Display
Control Head -E87-. The request is sent via the data bus to the
Vehicle Electrical System Control Module -J519- and the -J519-
activates the A/C Compressor regulator Valve -N280- and reports
the actual current. Refer to Vehicle Diagnostic Tester in the
"Guided Fault Finding" function.
- If no or very little current is displayed as the measured
value, check the activation of the A/C Compressor Regulator
Valve -N280-. Refer to
→ Chapter "A/C Compressor Regulator Valve -N280-, Checking
Switch-On Signal".
- Activation of the A/C Compressor Regulator Valve -N280- is
performed by the Front A/C Display Control Head -E87- via the
Vehicle Electrical System Control Module -J519-. The activation
of the A/C Compressor Regulator Valve -N280- is displayed as the
measured value in the Vehicle Electrical System Control Module
-J519-. Refer to Vehicle Diagnostic Tester in the "Guided Fault
Finding " function.
- The actual current flowing through the A/C Compressor
Regulator Valve -N280- is measured by the Vehicle Electrical
System Control Module -J519- and is sent via the data bus to the
Front A/C Display Control Head -E87-. Refer to Vehicle
Diagnostic Tester in the "Guided Fault Finding" function.
- In the "read measured values" function, read out the
refrigerant circuit pressure measured by the refrigerant High
Pressure Sensor -G65-. The displayed pressure goes over the
value for a A/C compressor that is switched off. Refer to
Vehicle Diagnostic Tester in the "Guided Fault Finding"
Function.
Note
- The pressure displayed in the displayed measured value does
not change and the A/C compressor activation is OK. Refer to
Vehicle Diagnostic Tester in the "Guided Fault Finding"
function. Check again whether the A/C compressor is actually
driven and the A/C Compressor Regulator Valve -N280- is
activated. If the A/C compressor is being driven and the A/C
Compressor regulator valve -N280- is activated, there is a
malfunction in the refrigerant circuit. Bring the vehicle to a
workshop that has the necessary tools and where the work can be
performed accordingly by qualified personnel. Refer to
→ Refrigerant R134a Servicing; Rep. Gr.87; A/C System, General
Information. If the A/C compressor control is not OK,
then inform the workshop of the problem at hand.
- The A/C Compressor Regulator Valve -N280- is activated by
the Front A/C Display Control Head -E87- (via the Vehicle
Electrical System Control Module -J519-) so that the temperature
of the air downstream from the evaporator reaches the specified
value (approximately 2 to 5 ºC (35.6 to 41 ºF) ).
- After starting the vehicle, a value greater than 0.55 A is
displayed for the activation of the A/C Compressor Regulator
Valve -N280- depending on the measured temperature, the engine
speed and the electrical system voltage. As soon as the
temperature measured by the Evaporator Vent Temperature Sensor
-G263- approaches the specified value, activation is canceled
and the compressor output is thus reduced.
- Under certain operating conditions, moisture in the
refrigerant circuit can lead to ice build-up on the A/C
Compressor Regulator Valve -N280- (and on the expansion valve).
This ice build-up interferes with A/C compressor regulation. The
evaporator is cooled too intensely and freezes. The freeze-up of
the evaporator can be the cause for various customer complaints.
Refer to
→ Chapter "Localizing Malfunction for Ice Build-Up on
Evaporator".
- Push the button for the recirculating air mode on the Front
A/C Display Control Head -E87- (the symbol for "recirculating
air mode" in the recirculation button
turns on).
- Set engine speed of 2000 rpm (start of time measurement).
- In the "read measured values" function, read out the
measured value of the Evaporator Vent Temperature Sensor -G263-.
Refer to Vehicle Diagnostic Tester in the "Guided Fault Finding"
function.
- Use a thermometer to measure the temperature of the air from
the vent in the rear center console.
- Compare the displayed value (for the Evaporator Vent
Temperature Sensor -G263-) with the values in the diagram.
A - Air temperature measured by the Evaporator Vent Temperature
Sensor -G263- (after evaporator in the front heater and A/C
unit)
B - Ambient temperature
C - Permissible tolerance range
Note
Depending on vehicle equipment, there are different versions
of the A/C system for the Audi Q7. Make sure to use the correct
version and pay attention to the allocation of different
components. Refer to
→ Chapter "A/C System Versions" and Parts Catalog.
- Depending on the ambient temperature, the measured air
temperature after the front evaporator (measured value of the
Evaporator Vent Temperature Sensor -G263-) must be within stated
tolerance range -C- after five
minutes.
- The measured temperatures from the vents of the rear center
console correspond to the temperature measured by the Evaporator
Vent Temperature Sensor -G263-. Permitted variance to the
measured value of the front Evaporator Vent Temperature Sensor
-G263- maximum + 9 ºC (48.2 ºF) (on a vehicle with a "Low"Mid"
or "Mix" A/C system with or without a Rear A/C Display Control
Head -E265- the version -A- and + 6
ºC /- 3 ºC (42.8 ºF/26.6 ºF) for a vehicle with a "High" A/C
system (a rear heater and A/C unit and a version
-B-Rear A/C Display Control Head
-E265-) but not lower than +1 ºC (33.8 ºF).
Note
- If the required values for the front are not reached, check
the measured value of the Evaporator Vent Temperature Sensor
-G263-. Additionally compare the displayed measured value of the
Sensor Evaporator Vent Temperature -G263- with the measured
values of the Left Front Upper Body Vent Temperature Sensor
-G385- and Right Front Upper Body Vent Temperature Sensor -G386-
with each other.
- If the measured value of the Evaporator Vent Temperature
Sensor -G263- only slightly deviates from the measured value for
the Left Front Upper Body Vent Temperature Sensor -G385- and the
Right Front Upper Body Vent Temperature Sensor -G386-. Determine
the malfunction when there is a deviation from specified value.
Refer to
→ Chapter "Malfunction Determination in Case of Deviation from
Target Value (Required Cooling Output of Front A/C System not
Achieved)".
- If the measured value of the Evaporator Vent Temperature
Sensor -G263- is greater than the measured value of the Left
Front Upper Body Vent Temperature Sensor -G385- or the Right
Front Upper Body Vent Temperature Sensor -G386-, check the
Evaporator Vent Temperature Sensor -G263- for proper
installation (refer to
→ Chapter "Evaporator Vent Temperature Sensor -G263-, Removing
and Installing") and perform an electrical test for
this sensor. Refer to Vehicle Diagnostic Tester in the "Guided
Fault Finding" function.
- The A/C system function can be recognized, for example, when
the refrigerant line "low pressure side" (wide line in the
plenum chamber between the expansion valve and the refrigerant
line with the inner heat exchanger under the left fender) cools
down and the refrigerant line "high pressure side" (narrow line
between the inner heater core and the expansion valve) warms up.
Refer to
→ Chapter "System Overview - Refrigerant Circuit with Rear
Heater and A/C Unit".
- If the deviation of the rear measured value from the front
measured value is too great. Refer to
→ Chapter "Malfunction Determination if Cooling Output of Front
A/C System is OK but Required Values not Achieved in Rear".
If the measured value of the Evaporator Vent Temperature
Sensor -G263- (and thus the cooling output of the front A/C
system) is OK and if there is no complaint, the cooling output
test ends.
- If the measured value of the Evaporator Vent Temperature
Sensor -G263- (and thus the cooling output of the A/C system) is
not OK, determine the malfunction causing the deviation from the
target value (the required cooling output is not reached). Refer
to
→ Chapter "Malfunction Determination in Case of Deviation from
Target Value (Required Cooling Output of Front A/C System not
Achieved)".
- If the measured value of the Evaporator Vent Temperature
Sensor -G263- (and thus the front A/C system cooling output) is
OK and if there is a complaint that the front A/C system vent
temperatures are too high or differ, check the activation of the
temperature doors in the front heater and A/C unit. Refer to
→ Chapter "Heat Output and Temperature Door Activation,
Checking".
- If the measured value of the Evaporator Vent Temperature
Sensor -G263- (and thus the front A/C cooling output) is OK and
if there is a complaint that the rear vent temperatures are too
high or differ in vehicles with a "High" A/C system (with a
version -B-Rear A/C Display Control
Head -E265-, check rear A/C cooling output. Refer to
→ Chapter "Malfunction Determination if Cooling Output of Front
A/C System is OK but Required Values not Achieved in Rear".
- If the measured value of the Evaporator Vent Temperature
Sensor -G263- (and thus the front A/C cooling output) is OK, and
there is a concern about the cooling output from the rear vents
(excessive or different temperatures of the air from the rear
vents), on vehicles with a "Low"Mid" or "Mix" A/C cooling
output (with our without version -A-Rear
A/C Display Control Head -E265-), check the activation of the
temperature control doors in the front heater and A/C unit.
Refer to
→ Chapter "Heat Output and Temperature Door Activation,
Checking".
- If the measured value of the Evaporator Vent Temperature
Sensor -G263- (and thus the front A/C cooling output) is OK, and
there is a complaint that the temperature of the air from the
rear vents is too low or there is a lack of air from the rear
vents after a while in vehicles with a "High" A/C system (with a
version -B-Rear A/C Display Control
Head -E265-), check the cooling output of the rear A/C system.
Refer to
→ Chapter "Malfunction Determination if Cooling Output of Front
A/C System is OK but Required Values not Achieved in Rear".
READ NEXT:
- In the "read measured values" function, select the display
group with the measured values for the A/C compressor activation
and the refrigerant circuit pressure. Refer to Vehicle
Diagnostic
Note
Depending on vehicle equipment, there are different versions
of the A/C system for the Audi Q7. Make sure to use the correct
version and pay attention to the allocation of different
co
Note
Depending on vehicle equipment, there are different versions
of the A/C system for the Audi Q7. Make sure to use the correct
version and pay attention to the allocation of different
co
SEE MORE:
General information
Applies to: vehicles with adjustable head restraints
Fig. 60 Correctly-adjusted head restraint
Make sure that:
The upper edge of the head restraint is as even
as possible with the top of your head
The head restraint is as close as possible to the
back of the head
The head
General Information - Infrared System
The infrared system (9R1) supports the driver during trips
in the dark. The infrared system image shows in the instrument
cluster a thermal image of the area ahead of the vehicle. The
range of view of approximately 300 m extends well beyond the
range of the