Audi Q5: Pressures, Checking
- Observe the test requirements. Refer to
→ Chapter "Test Requirements".
- Turn off the ignition.
- Connect the A/C service station. Refer to
→ Chapter "A/C Service Station, Connecting".
Vehicles with an electric operated valves in the refrigerant
circuit, which cannot be opened without power (for example the
Audi Q7 e-tron):
Note
On vehicles with high-voltage system and additional
functions of the A/C system ("heat pump operation" or "cooling
the high-voltage battery") valves may be installed in the
refrigerant circuit which cannot be opened without power. These
valves are opened and closed for example via a step motor and
after switching off the ignition are no longer activated. To
check the pressures in the refrigerant circuit with the A/C
system switched off no areas may be closed be closed, for this
reason the valves must be opened before these procedures. Refer
to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit and the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.
- Open the electrically activated valves, which to now open
without power using the Vehicle Diagnostic Tester in the "Guided
Fault Finding" function.
All Vehicles
- Take the pressure gauge readings (two possible results):
- Pressure in refrigerant circuit lower than indicated in
table
- Pressure in refrigerant circuit in line with table or higher
Note
- Temperature of refrigerant circuit components should be
equal to ambient temperature. Pressure will deviate from values
in table if individual components of refrigerant circuit are
warmer or colder.
- At absolute pressure, 0 bar/psi corresponds to absolute
vacuum. Normal ambient pressure (positive pressure) corresponds
to 1 bar (14.5 psi) absolute pressure. 0 pressure corresponds to
an absolute pressure of 1 bar (14.5 psi) on most pressure gauges
(indicated by -1 bar (-14.5 psi) below 0).
- For vehicles with High Pressure Sensor -G65-, Refrigerant
Circuit Pressure Sensor -G805- or A/C Pressure/Temperature
Sensor -G395-, etc. for which measured pressure is displayed in
measured value block, pressure measured should coincide. Use the
Vehicle Diagnostic Tester ("OBD" or "Guided Fault Finding for
the A/C system") and
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual).
- Pressure is measured in different units: 1 MPa (145 psi)
corresponds to 10 bar (145 psi) positive pressure. 1 bar (14.5
psi) absolute pressure corresponds to 0 bar/psi positive
pressure and thus to the ambient pressure (atmospheric
pressure).
Pressure in refrigerant circuit lower than indicated in
table
Not enough refrigerant in refrigerant circuit
- Determine refrigerant circuit leaks. Refer to
→ Chapter "Refrigerant Circuit, Determining Leaks ".
- Check the pressure relief valve.
If pressure relief valve has responded:
- Check the coolant fan activation.
- Check the refrigerant lines and hoses for cross-section
constrictions caused by inadequate bending radii.
- Check the refrigerant lines and hoses for external damage.
- If no fault is found, clean the refrigerant circuit (flush
using refrigerant R134a. Refer to
→ Chapter "Refrigerant Circuit, Cleaning (Flushing), with
Refrigerant R134a"; or blow through using compressed
air and nitrogen. Refer to
→ Chapter "Refrigerant Circuit, Flushing with Compressed Air and
Nitrogen").
Pressure in refrigerant circuit in line with table or higher
- Start the engine or activate the ready mode (for example on
vehicles with a high-voltage system).
- Set the A/C system to maximum cooling output.
Note
- On vehicles with A/C Compressor Regulator Valve -N280-, the
control current can be read in the measured value block. Use the
Vehicle Diagnostic Tester (Function "OBD" or "Guided Fault
Finding" of the Air Conditioning) and
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; A/C
Compressor (vehicle-specific repair manual).
- On vehicles with an Electrical A/C Compressor -V470- read
out the A/C Compressor Speed Sensor using the different control
modules (for example via the respective climate control module
or the Thermal Management Control Module -J1024-) using the
Vehicle Diagnostic Tester in the "Guided Fault Finding"
function.
Vehicles with a Mechanically Driven A/C Compressor
If A/C compressor is not driven with the engine running or
regulating valve is not actuated:
- Determine and eliminate cause, for example by checking A/C
system DTC memory.
- Observe the test conditions.
- Check the A/C Clutch -N25- voltage supply. If it is OK,
repair the A/C clutch.
- Check the A/C Compressor Regulator Valve -87- activation.
Use the Vehicle Diagnostic Tester (Function "OBD" or "Guided
Fault Finding" of the Air Conditioning) and
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; A/C
Compressor (vehicle-specific repair manual).
Note
- If the low pressure switch was removed to connect the
service station, bridge the electrical connections in the
corresponding connector for the pressure measurement.
- A/C compressor is driven by the engine via A/C Clutch -N25-.
- The A/C Compressor Regulator Valve -N280- is activated by
the Front A/C Display Control Head -E87- or Climatronic Control
Module -J255-. Use the Vehicle Diagnostic Tester (Function "OBD"
or "Guided Fault Finding" of the Air Conditioning) and
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual).
Vehicles with an Electrical A/C Compressor -V470- (Vehicles
with a High-Voltage System)
If the electrical A/C Compressor is not activated while the
ready mode is active:
- Check the activation of the A/C compressor via the
respective control module. Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit and use the Vehicle Diagnostic Tester in the
"Guided Fault Finding" function.
All Vehicles
- Checking pressures on vehicles with a restrictor and
reservoir (with internally regulated A/C compressor). Refer to
→ Chapter "Checking Pressures for Vehicles with Restrictor and
Reservoir (with Internally Regulated Compressor)".
- Checking pressures on vehicles with an expansion valve and
receiver/dryer (with internally regulated A/C compressor). Refer
to
→ Chapter "Checking Pressures on Vehicles with Expansion Valve
and Receiver/Dryer (with Internally Regulated Compressor)".
- Checking pressures for vehicles with restrictor, reservoir
and A/C Compressor Regulator Valve -N280- (externally regulated
A/C compressor). Refer to
→ Chapter "Vehicles with Restrictor, Reservoir and A/C
Compressor Regulator Valve -N280- (Externally Regulated A/C
Compressor), Checking Pressures".
- Checking pressures on vehicles with restrictor,
receiver/dryer and A/C Compressor Regulator Valve -N280-
(externally regulated compressor). Refer to
→ Chapter "Vehicles with Restrictor, Receiver/Dryer and A/C
Compressor Regulator Valve -N280-, Checking Pressures,
Externally Regulated Compressor".
- Check the pressures on vehicles with an electrically-driven
A/C compressor (Audi A3 e-tron, Audi Q5 hybrid, Audi Q7 e-tron
etc.). Refer to
→ Chapter "Checking Pressures on Vehicles with Electrically
Driven A/C Compressor (Vehicles with Hybrid Drive)".
READ NEXT:
General Information
Note
Connect the A/C service station. Refer to
→ Chapter "A/C Service Station, Connecting".
Observe the test requirements. Refer to
→ Chapter "Pressures,
General Information
Note
Connect the A/C service station. Refer to
→ Chapter "A/C Service Station, Connecting".
Observe the test requirements. Refer to
→ Chapter "Pressures,
Specified Values for the Refrigerant Circuit Pressures
Note
Connect the Air Conditioning (A/C) service station. Refer to
→ Chapter "A/C Service Station, Connecting".
Observe the test
SEE MORE:
Special tools and workshop equipment
required
Press Plate -VW401-
Press Plate -VW402-
Press Piece - Rod -VW408A-
Press Piece - Rod -VW411-
Press Piece - 37mm -VW416B-
Press Piece - Multiple Use -VW447H-
Hose Clip Pliers -VAG1275A-
Torque Wrench 1331 5-50Nm -VAG1331-
Torque Wrench 1332 40-
Front Information Display Control Head -J685-
Note
Unlisted connector terminals are not assigned.
"chorus"(T10u) red
1 - CAN Bus (display) from the Radio -R-
2 - CAN Bus (display) from the Radio -R-
3 - Voltage Supply from the Radio - R-
4 - Terminal 3