Audi A4: General Information
High pressure side are the condenser, receiver/dryer and
restrictor or expansion valve to separate the high and low
pressure liquid ends.
High pressure results from the restrictor or expansion valve
forming a constriction and causing the refrigerant to
accumulate, thus leading to an increase in pressure and
temperature.
Excess pressure occurs if too much refrigerant or
refrigerant oil is used, the condenser is contaminated, the
radiator fan is malfunctioning, the system is blocked or there
is moisture in the refrigerant circuit (icing-up of restrictor
or expansion valve).
Low pressure side are the evaporator, reservoir, evaporator
temperature sensor and A/C compressor to separate high and low
pressure gas ends.
A drop in system pressure can be caused by loss of
refrigerant, the restrictor or expansion valve (no
constriction), a malfunctioning A/C compressor or an iced-up
evaporator.
Mechanically Driven A/C Compressor
The A/C compressor is driven by a ribbed belt or a input
shaft, which is driven by the vehicle engine.
A/C Compressor with A/C Clutch
- An electromagnetic clutch -A-
attached to A/C compressor provides the power link between the
ribbed belt pulley -B- and A/C
compressor crankshaft with A/C system switched on.
- An overload safeguard attached to the clutch plate or in the
A/C compressor solenoid coil is tripped if the compressor does
not move freely, thus protecting the belt drive against
overload.
A/C Compressor without A/C Clutch
- An overload safeguard attached to the pulley of the
compressor -B- is tripped if the
compressor does not move freely, thus protecting the belt drive
against overload.
All A/C Clutch
The A/C compressor extracts the refrigerant gas from the
evaporator, compresses it and relays it to the condenser.
Note
- The A/C compressor contains refrigerant oil, which can be
mixed with refrigerant R134a under any temperature.
- The data plate lists the type of refrigerant required for
the A/C compressor. A regulator valve regulates pressure within
the specified range (control characteristics) on the low
pressure side.
- A/C compressors with or without an A/C clutch are currently
controlled externally by a regulator valve
-C-.
- On A/C compressors without an A/C clutch, the engine is only
to be started following complete assembly of the refrigerant
circuit.
- So that the A/C compressor does not get damaged when the
refrigerant circuit is empty, the A/C clutch is turned off and
the A/C Compressor Regulator Valve -N280- is no longer activated
(A/C compressor runs at idle with engine).
- If the refrigerant circuit is empty, a A/C compressor
without A/C Clutch -N25- with (A/C Compressor Regulator Valve
-N280-) is switched to internal lubrication by way of a valve.
- Depending on the A/C compressor version, there may be a
valve installed on the high pressure side of the A/C compressor,
which prevents the liquid refrigerant from flowing back into the
compressor once the A/C is turned off. If an A/C compressor with
this valve is installed in a vehicle with a refrigerant circuit
having an expansion valve, then it may take some time until the
pressure in the high pressure side decreases (the expansion is
cold and the pressure in the low pressure side quickly increases
after it is turned off, the expansion valve closes and the
refrigerant flows slowly into the low pressure side). If the A/C
compressor is switched on, the pressure on the low pressure side
goes down, the expansion valve open and the refrigerant can flow
of the low pressure side.
- The electromagnetic clutch -A-
is activated only when the regulator valve
-C- is activated on an A/C compressor with an
electromagnetic clutch -A- and with
a regulator valve -C-. Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit.
Electrically Driven A/C Compressor for Vehicles with High Voltage
System
Vehicles with a High-Voltage System (Hybrid Vehicles)
Extremely Dangerous Due to High-Voltage
The high-voltage system is under high-voltage. Death or serious
bodily injury by electric shock.
- Individuals with electronic/medical life- and health sustaining
machines in or on their person cannot perform any work on high-voltage
systems. Life- and health sustaining machines are for example pain
killer pumps, implanted defibrillators, pacemakers, insulin pumps, and
hearing aids.
- Have the high-voltage system de-energized by a qualified person.
There is a Risk Of Injury from the Engine Starting Unexpectedly
On electric - hybrid vehicles an active ready mode is difficult to
identify. Parts of the body can be clamped or pulled.
- Turn off the ignition.
- Place the ignition key outside of the vehicle interior.
Risk of Damaging the High-Voltage Cables
Misuse can damage the insulation of high-voltage cables or
high-voltage connectors.
- Never support objects on the high-voltage cables and the
high-voltage connectors.
- Never support tools on the high-voltage cables and the high-voltage
connectors.
- Never sharply bend or kink the high-voltage cables.
- When connecting pay attention to the coding of the high-voltage
connectors.
- For all procedures on vehicles with high-voltage system pay
attention to the additional warning message for these vehicles.
Refer to
→ Chapter "Warnings when Working on Vehicles with High Voltage
System".
- If procedures are necessary near components of the
high-voltage system "perform a visual inspection of the damage
of the high-voltage components and lines". Refer to
→ Chapter "Performing a Visual Inspection of Damage to High
Voltage Components and Cables".
- If work on the components of the high-voltage system is
necessity, de-energize the high-voltage system. Refer to
→ Rep. Gr.93; High-Voltage System, De-Energizing or
→ Electrical Equipment; Rep. Gr.93; High-Voltage System,
De-Energizing.
- Charge the vehicle battery, for example, using the Battery
Charger -VAS5904- in the battery support mode to minimize the
number of automatic starts during the test- and measuring
procedures while the ready mode is active. Refer to
→ Electrical Equipment General Information; Rep. Gr.27; Battery,
Charging and
→ High Voltage Vehicle General Information; Rep.
Gr.93; High-Voltage System General Warnings.
- For testing and measurement procedures that require the
ready mode to be active or the ignition to be switched on, the
selector lever must be in the "P" position and the parking brake
must be activated. The required tools must be placed so that
they do not come into contact with any rotating components in
the engine and they must also not go into the vicinity of the
rotating components when the engine is running.
Electrically-Driven A/C Compressor
WARNING
Risk of short circuit
The A/C compressor works with up to 288 volts at 800
to 8,600 RPM.
Do not touch the A/C compressor when the ignition is
turned on or when the drive machines are activated
because of the short circuit risk.
- The A/C compressor extracts the refrigerant gas from the
evaporator, compresses it and relays it to the condenser.
- The electric motor for the A/C compressor is powered with
voltage from the Electric Drive Power and Control Electronics
-JX1-.
- The A/C Compressor Control Module -J842- integrated in the
A/C compressor controls the rotation and thereby the output for
the A/C compressor (Electrical A/C Compressor -V470-)
corresponding with the Data bus receiving requirements. Use the
Vehicle Diagnostic Tester in the "Guided Fault Finding" Function
for the A/C System and the Battery Regulation.
- There is no A/C Compressor Regulator Valve -N280- installed
in the electrically-driven A/C compressor.
- Check the attachment points on the A/C compressor and the
bracket prior to installation. The contact surfaces must be
clean and free of rust and grease. Otherwise, repair the contact
surfaces with the Contact Surface Cleaning Set -VAS6410-. Refer
to
→ Electrical Equipment General Information; Rep. Gr.97; Wire and
Connector Repair.
Note
- Check the amount of refrigerant oil in the new A/C
compressor if the A/C Compressor Control Module -J842- is
faulty. Do not flush the refrigerant circuit with R134a.
- The A/C Compressor Control Module -J842- and the Electrical
A/C Compressor -V470- are one component and are currently not
able to be separated.
- There is no A/C Compressor Regulator Valve -N280- installed
in the electrically driven A/C compressor. The A/C compressor
output is regulated externally by the A/C compressor speed.
Refer to
→ Wiring diagrams, Troubleshooting & Component locations
and use the Vehicle Diagnostic Tester in the "Guided Fault
Finding" Function for the A/C System and the Battery Regulation.
- The electrically-driven A/C compressor functions according
to the principle of a spiral charger (similar to a G-charger).
- The A/C compressor contains refrigerant oil, which can be
mixed with refrigerant R134a under any temperature.
- The data plate lists the type of refrigerant required for
the A/C compressor.
- The installed electronics are controlled by the speed of the
A/C compressor power output (and the pressure on the low
pressure side) within the specified range (control
characteristic).
- The engine should only be started if the refrigerant circuit
is completely assembled.
- The A/C compressor is equipped with a protected oil supply,
this prevents A/C compressor damage in the event that the system
is empty. This means that approximately 40 to 50 cm3
of refrigerant oil remains in the A/C compressor.
- The electrically-driven A/C compressor has a relief valve
like the mechanically-driven A/C compressor.
- Hybrid drive on vehicles with battery cooling is only
possible with a fully charged A/C system in which there are no
stored errors. Use the Vehicle Diagnostic Tester in the "Guided
Fault Finding" Function for the A/C System and the Battery
Regulation.
- After the installation of the electrically-driven A/C
compressor and the subsequent filling of the refrigerant
circuit, start the A/C compressor for the first time using the
"compressor intake" function for the basic setting. The A/C
compressor may otherwise become damaged if before installation,
refrigerant oil was improperly stored in the A/C compressor
compression chamber. Use the Vehicle Diagnostic Tester in the
"Guided Fault Finding" Function for the A/C System and the
Battery Regulation.
- Only activate the electrically-driven A/C compressor when
the refrigerant circuit is filled. The A/C compressor may become
damaged if the A/C compressor is run when the refrigerant
circuit is empty. Use the Vehicle Diagnostic Tester in the
"Guided Fault Finding" Function for the A/C System and the
Battery Regulation.
READ NEXT:
The condenser conducts heat from compressed refrigerant gas
to the ambient air.
This condenses the refrigerant gas to fluid.
Note
Depending on the version of the refrigerant circuit, the
r
The reservoir collects the vaporized and gaseous mixture
coming from the evaporator to ensure the compressor only
receives gaseous refrigerant. Gaseous refrigerant is formed from
the vapor.
The ref
The expansion valve atomizes the streaming refrigerant and
controls the flow quantity so that the vapor is gaseous only at
the evaporator outlet, depending on the heat transmission.
Note
B
SEE MORE:
Applies to: vehicles with Audi adaptive cruise control
Fig. 110 Operating lever: operating adaptive cruise control
Fig. 111 Operating lever: changing the speed
Switching on
To switch on the adaptive cruise control, pull
the lever up to position 1 until it engages.
Storing the speed and activat
Overview - Airbag Control Module
1 - Center Tunnel
2 - Nut
9 Nm
Quantity: 4
The thread must be paint and contaminant free, nut and ground pins serve
as ground connection for the control module.
3 - Airbag Control Module -J234-
Removing and installing. Refer to