Audi Q5: A/C Pressure Switch -F129-
Note
Switch pressures, removing and installing switches as well
as switch arrangement and version. Refer to vehicle specific
refrigerant circuit
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual).
This pressure switch has 3 functions:
1. Switches the coolant fan to the next higher level when
the pressure in the refrigerant circuit increases (approximately
16 bar (232 psi) ).
2. Switches off A/C system if pressure is excessive
(approximately 32 bar (464 psi) ), for example because of
insufficient engine cooling.
3. Switches off A/C system if pressure is insufficient
(approximately 2 bar (29 psi) ), for example loss of refrigerant.
Note
A/C Pressure Switch -F129- replaces the A/C Refrigerant High
Pressure Switch -F23-, A/C Refrigerant Low Pressure Switch -F73-
and the Magnetic Clutch High Pressure Switch -F118-.
High Pressure Sensor -G65-, Refrigerant Circuit Pressure Sensor -G805-
- This High Pressure Sensor -G65- is installed instead of the
A/C Pressure Switch -F129- or the A/C Pressure/Temperature
Sensor -G395-.
- The Refrigerant Circuit Pressure Sensor -G805- replaces the
High Pressure Sensor -G65- on specific vehicles from a specific
version and from a specific date of manufacture.
- When a voltage is applied, a version of the High Pressure
Sensor -G65- generates a square wave signal and the others a
data telegram. This signal changes along with pressure in the
system. When voltage is applied, the other versions and the
Refrigerant Circuit Pressure Sensor -G805- exchange information
with the Data bus (i.e. via the "LIN-Bus") with the
corresponding control module. Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual).
- On Audi A3 from MY 2005 and Audi Q3. a High Pressure Sensor
-G65- is installed, for example, which emits its measured values
to the corresponding control module (for example to the A/C
Control Module -J301- or the Climatronic Control Module -J255-).
On Audi Q7 from MY 2016, a High Pressure Sensor -G65- is
installed, for example, which sends its measured values via a
"LIN Bus". Use the Vehicle Diagnostic Tester ("OBD" function or
A/C system "Guided Fault Finding") and
→ Wiring diagrams, Troubleshooting & Component locations.
- The Refrigerant Circuit Pressure Sensor -G805- is installed
on the Audi A3 from MY 2013, for example. It exchanges
information with the corresponding control module (on Audi A3,
the A/C Control Module -J301- or the Climatronic Control Module
-J255-) via a data bus cable. Refer to
→ Wiring diagrams, Troubleshooting & Component locations
- The A/C Pressure/Temperature Sensor -G395-, the Refrigerant
Circuit Pressure Sensor -G805- and the High Pressure Sensor
-G65- are available in different versions. Currently the
sensor's only exterior difference is the parts number.
Therefore, make sure that the part numbers are correctly
allocated when replacing them (part number Parts Catalog ).
Reason: These sensors produce different signals that can only be
evaluated by the respective control modules using the
→ Vehicle Diagnostic Tester (function "OBD" or "Guided Fault Finding" for the A/C system). Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual).
- The High Pressure Sensor -G65- and the Refrigerant Circuit
Pressure Sensor -G805- only transmits the measured value for the
refrigerant circuit pressure to the connected control module.
The A/C Pressure/Temperature Sensor -G395- transmits the
measured value for the refrigerant circuit pressure and the
measured temperature to the connected control module. Even
though only the pressure signal is evaluated on a vehicle, an
A/C Pressure/Temperature Sensor -G395- is not and must not be
installed on a vehicle for which a High Pressure Sensor -G65- or
a Refrigerant Circuit Pressure Sensor -G805- is designed. Refer
to Parts Catalog.
- The downstream control modules (Radiator Fan Control Module,
Engine Control Module, Front A/C Display Control Head -E87- or
Climatronic Control Module -J255-, etc.) use this signal to
calculate the refrigerant circuit pressure and activate the
radiator fans, the motor, and the A/C Clutch -N25- if necessary,
or to change the activation of the A/C Compressor Regulator
Valve -N280-. Use the Vehicle Diagnostic Tester ("OBD" or "Guided Fault Finding" function). Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit (vehicle-specific repair manual).
A/C Pressure/Temperature Sensor
There are different versions of this sensor with different
functions and with different names. For exact name, allocation
and notes doe the respective function, refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit (vehicle-specific repair manual).
WARNING
There is a risk of freezing.
Refrigerant may leak out if refrigerant circuit is
not discharged.
There are different versions of this sensor (sensor
for a connection to the refrigerant circuit with or
without the valves). Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview -
Refrigerant Circuit (vehicle-specific repair
manual).
- Before loosening the threaded connection of the
sensor check the version. Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview -
Refrigerant Circuit.
- On a sensor for the connection on the refrigerant
circuit without a valve. The refrigerant must be
extracted before loosening the threaded connection. If
sensor is not removed within 10 minutes after
extraction, pressure may build up in refrigerant circuit
by renewed evaporation. Extract the refrigerant again.
Sensor for a connection with the valve on the refrigerant
circuit
Note
- There are different versions of this sensor with different
functions and with different names. The following illustrated
A/C Pressure/Temperature Sensor -G395- is for example installed
on an Audi A4, Audi Q5, and Audi Q5 hybrid. Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview- Refrigerant Circuit.
- There are various designations, depending on the function
and the vehicle. Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit.
Possible names for this sensor
- A/C Pressure/Temperature Sensor -G395- (for example on Audi
Q5 hybrid)
- High Pressure Sensor -G65- (for example on Audi A4)
- Refrigerant Circuit Pressure Sensor -G805- (for example on
Audi A3 e-tron)
Note
The Refrigerant Circuit Pressure Sensor -G805- is installed
instead of for example the High Pressure Sensor -G65- or the A/C
Pressure/Temperature Sensor -G395-. Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit.
- The A/C Pressure/Temperature Sensor -G395-, the Refrigerant
Circuit Pressure Sensor -G805- and the High Pressure Sensor
-G65- are available in different versions. Currently the
sensor's only exterior difference is the parts number.
Therefore, make sure that the part numbers are correctly
allocated when replacing them (part number from the Parts
Catalog). Reason: These sensors produce different signals that
can only be evaluated by the respective control modules using
the Vehicle Diagnostic Tester (function "OBD" or "Guided Fault
Finding" for the A/C system). Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual).
- When voltage is applied, the A/C Pressure/Temperature Sensor
-G395- (and the Refrigerant Circuit Pressure Sensor -G805-
exchange information via the Data bus (for example via the
"LIN-Bus") with the corresponding control module. The relevant
control module uses this information to calculate the pressure
(and temperature) in the refrigerant circuit and any faults
detected are signaled to the control module.
- The A/C Pressure/Temperature Sensor -G395- transmits the
measured value for the refrigerant circuit pressure and the
measured temperature to the connected control module. The
Refrigerant Circuit Pressure Sensor -G805- only transmits the
measured value for the refrigerant circuit pressure to the
connected control module. Even if only the pressure signal is
evaluated on most vehicles, no Refrigerant Circuit Pressure
Sensor -G805- is or will be installed in a vehicle in which a
A/C Pressure/Temperature Sensor -G395- is designed. Refer to the
Parts Catalog.
- The temperature measured by the A/C Pressure/Temperature
Sensor -G395- differs from the actual refrigerant temperature in
the refrigerant circuit because of the A/C Pressure/Temperature
Sensor -G395- design and its component location. Because of
this, it is not currently evaluated and is not used to regulate
the A/C system. Refer to
→ Heating and Air Conditioning; Rep. Gr.87; System Overview -
Refrigerant Circuit (vehicle-specific repair manual).
- This information is used for example by the Climatronic
Control Module -J255- control head or the Vehicle Electrical
System Control Module -J519- to calculate the pressure in the
refrigerant circuit and to actuate the downstream control
modules (radiator fan control module, Engine Control Module
etc.) via the data bus system. These control modules then
actuate, for example, the A/C Cutch -N25-, the radiator fan and
the motor. Use the Vehicle Diagnostic Tester (function "OBD" or "Guided Fault Finding" and,
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual).
Sensor for a Connection without the Valve on the Refrigerant
Circuit
Note
- There are different versions of this sensor with different
functions and with different names. The following illustrated
A/C Pressure/Temperature Sensor -G395- is for example installed
on an Audi Q7 e-tron. Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview- Refrigerant Circuit.
- There are various designations, depending on the function
and the vehicle. Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit.
Possible names for this sensor
- A/C Pressure/Temperature Sensor -G395- (for example on Audi
Q7 e-tron)
- A/C Pressure/Temperature Sensor 2 -G826- (for example on
Audi Q7 e-tron)
- A/C Pressure/Temperature Sensor 3 -G827- (for example on
Audi Q7 e-tron)
There are different versions of this sensor
-A-, currently the sensor's only
exterior difference is the part number or if the part number is
the same the imprinted designation -B-.
For this reason pay attention to the correct allocation (part
number and designation). Refer to the Parts Catalog and
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit.
This sensor exchanges the information with the respective
control module via the data bus (for example via the "LIN Bus")
when creating tension. The relevant control module uses this
information to calculate the pressure (and temperature) in the
refrigerant circuit and any faults detected are signaled to the
control module. Use the Vehicle Diagnostic Tester in the "Guided
Fault Finding" function.
With this information the respective control module
calculates the refrigerant circuit pressure and activates the
downstream control module or components (radiator fan control
module, pumps, valves etc.) via the data bus according to the
specifications. Use the Vehicle Diagnostic Tester in the "Guided
Fault Finding" function and refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit (vehicle-specific repair manual).
READ NEXT:
Note
Switch pressures, removing and installing switches as well
as switch arrangement and version. Refer to vehicle specific
refrigerant circuit
→ Heating, Ventilation and Air Condit
General Information
Caution
When performing work on refrigerant circuit, observe
all generally applicable safety precautions and pressure
container regulations.
The pressures and temperatur
General Information
Indicators on pressure gauge
1 - Temperature scale for refrigerant R134a CF3-CH2F or
CH2F-CF3.
2 - Pressure scale
Note
Pressure is measured in differen
SEE MORE:
Removing
WARNING
Note the following before removing the steering
column:
Create a sketch showing the:
routing of the electrical wiring harnesses
securing of the electrical wiring harnesses
cable tie locations.
This especially applies to the wiring harness to the
Electronic Steering C
Applies to vehicles: with Audi adaptive cruise control
Braking guard: Off
This driver message appears if the system is
turned off via the radio/MMI. Otherwise, if the
system is turned off, the information appears every
time shortly after the start of the trip.
The diver message also appears if the