Audi Q3: Refrigerant Circuit Components
Caution
Non-approved tools or materials such as leak sealing
additives can cause damage or malfunctions in the
system.
Only use tools and materials approved by the
manufacturer.
The warranty is voided if non-approved tools or
materials are used.
- Any refrigerant circuit components submitted for quality
observation must be sealed (use the caps that come with the
replacement part).
- Replace damaged or leaking components of the refrigerant
circuit. Refer to
→ Chapter "Refrigerant Circuit Components, Replacing".
Note
To date, the following replacement parts (A/C compressor,
reservoir, evaporator and condenser) are filled with nitrogen
gas. This charge is being gradually discontinued. Little or no
pressure equalization is therefore noticeable on unscrewing
sealing plugs from replacement parts.
Refrigerant Circuit Components Allocation, High and Low Pressure Sides
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.
Condenser
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
receiver/dryer is installed (integrated) either on the condenser
or inside the condenser. Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual) and the Parts Catalog.
- The condenser is available in different versions and can be
differentiated only by the part number on the outside. For
version -1-, the condenser is
divided into two areas "2 way condenser". For version
-2-, the condenser is divided into
four areas "4 way condenser".
- This illustration shows a condenser with the receiver/dryer
-C- installed.
- The gaseous refrigerant enters at the connection
-A- into the condenser. The
refrigerant is then cooled inside the condenser and becomes
fluid.
- The liquid refrigerant collects in the receiver/dryer
-C- (with dryer) and flows through
the lower cooling area towards the connection
-B-.
- Depending on the design of the condenser (interior volumes,
delivery flow, etc.), the amount of the refrigerant that is
needed to fill the refrigerant circuit may vary. Therefore
always be sure of the correct version and allocation for the
condenser. Refer to
→ Chapter "Refrigerant R134a Capacities" and the
Parts Catalog.
Evaporator
The evaporator is available in different versions. Depending
on the version and the function, the necessary heat energy of
the air flow (for example, an evaporator in the A/C unit or in
the battery cooling module) or flowing coolant (for example near
the high voltage battery heat exchanger) is extracted for
refrigerant evaporation. Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual).
Note
Two versions of evaporator are described.
Evaporator in A/C Unit (or in Battery Cooling Module)
The fluid refrigerant evaporates in the evaporator pipe
coils. The heat required for this is extracted from the air
flowing on the evaporator ribbing. The air cools off.
Refrigerant evaporates and is extracted with the absorbed heat
by the A/C compressor.
A defined amount of refrigerant is supplied to the
evaporator by a restrictor or expansion valve. In systems with
expansion valve, the throughput is regulated so that only
gaseous refrigerant escapes the evaporator outlet.
Evaporator/High Voltage Battery Heat Exchanger (Chiller)
The liquid refrigerant evaporates in evaporator (heat
exchanger). The heat required for this is extracted from the
flowing refrigerant. The coolant cools, the refrigerant
evaporates and is extracted with the absorbed heat by the A/C
compressor.
A defined amount of refrigerant is supplied to the
evaporator by a restrictor (or expansion valve) and a shut off
valve. The throughput of the refrigerant (for example the
coolant) is regulated so that only gaseous refrigerant escapes
the evaporator outlet. Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual).
Heat Pump Operation Heater Core
The gaseous or vaporous refrigerant that is compressed by
the A/C compressor is liquefied in the A/C compressor
-A- and at the same time released
heat is transferred to the coolant flowing by. Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit.
Fluid Collector
In some operating conditions (for example heat pump
operation) the receiver/dryer (for example on the condenser) is
not incorporated in the refrigerant circuit. The fluid collector
-B- collects the refrigerant, and
saves it if a specific quantity of refrigerant is not needed and
directs it in an uninterrupted stream to the expansion valve (in
front of the evaporator in the heater and A/C unit) or to the
heat exchanger in the refrigerant circuit of the high-voltage
system. Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit.
Reservoir
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 refrigerant oil flowing in the circuit is not retained
in the reservoir as it has an oil drilling.
Moisture which has entered the refrigerant circuit during
repairs will be collected by a filter (desiccant bag) in the
reservoir.
Gaseous refrigerant is extracted with oil by the A/C
compressor.
Note
- Replace the reservoir if refrigerant circuit has been open
for a long time (beyond the normal repair time) and moisture has
penetrated inside, or if required due to a specific complaint.
Refer to
→ Chapter "Refrigerant Circuit Components, Replacing".
- Remove the sealing plugs -A-
and -B- only immediately before
installing.
- A desiccant bag in an unsealed reservoir is saturated with
moisture after a short period of time and unusable.
- When installing, note arrow for direction of flow if
necessary.
Restrictor
Restrictor in Front of the Evaporator
The restrictor creates a constriction. This restriction
reduces the flow and creates high and low pressure sides in the
refrigerant circuit. Before the restrictor the refrigerant which
is under a higher pressure is warm. After the restrictor the
refrigerant which is under a low pressure is cold. Before the
restriction there is a strainer for contaminants and after the
restriction there is a strainer, to atomize the refrigerant
before it reaches the evaporator.
Note
- Arrow -A- on restrictor points
to the evaporator.
- Replace after each opening of the circuit.
- There are different versions, therefore pay attention to the
different customer service information sources. Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit and (vehicle-specific
repair manual) and to the Parts Catalog .
Restrictor in Front of the High Voltage Battery Heat
Exchanger (Chiller)
The restrictor creates a constriction. This restriction
reduces the flow and creates high and low pressure sides in the
refrigerant circuit. Before the restrictor the refrigerant which
is under a higher pressure is warm. After the restrictor the
refrigerant which is under a low pressure is cold.
Note
- The illustration shows a refrigerant line
-A- with a fixed installed
restrictor -B- (without a strainer)
- The diameter of the illustrated variable orifice
-B- is approximately 0.7 mm.
Depending on the version of the refrigerant line this
constriction is either installed fixed in the refrigerant line
or only inserted. For the inserted version a strainer for
flowing deposits may be installed, which can be blocked by the
variable orifice.
- Before installing check for debris and if necessary clean or
replace.
- There are different versions, therefore pay attention to the
different customer service information sources. Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit and (vehicle-specific
repair manual) and to the Parts Catalog.
Receiver/Dryer
The receiver/dryer collects the fluid drops and then directs
them in an uninterrupted stream to the expansion valve. Moisture
which has entered the refrigerant circuit during repairs will be
collected by the desiccant bag in the receiver/dryer.
Note
- Replace the receiver/dryer if refrigerant circuit has been
open for a long time (beyond the normal repair time) and
moisture has penetrated inside, or if required due to a specific
complaint. Refer to
→ Chapter "Refrigerant Circuit Components, Replacing".
- Only remove sealing plugs shortly before installation.
- A desiccant bag in an unsealed receiver/dryer becomes
saturated with moisture after a short period of time and
unusable.
- When installing, note arrow for direction of flow if
necessary.
- Depending on the version of the refrigerant circuit, the
receiver/dryer is also installed (integrated) either on the
condenser or inside the condenser. Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual) and the Parts Catalog.
- The procedure is different for each complaint depending on
the version of the receiver/dryer and the dryer cartridge. If
the receiver/dryer, for example, is attached to the condenser,
then it can be replaced complete with the drying cartridge. If
the receiver/dryer, for example, is inside the condenser, then
the dryer cartridge, and any possible additional filters, can be
replaced separately, on most versions. If the receiver/dryer is
inside the condenser and there is absolutely no way to replace
the reservoir or the dry cartridge individually, then the entire
condenser must be replaced. Refer to
→Heating, Ventilation and Air Conditioning; Rep. Gr.87
and
→Heating, Ventilation and Air Conditioning; Rep. Gr.87
(vehicle-specific repair manual) and Parts Catalog.
- Depending on the construction of the refrigerant circuit,
the receiver can also be secured onto the condenser. Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual) and the Parts Catalog.
Expansion Valve
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
- Be sure to use the correct part number when replacing the
expansion valve. Refer to the Parts Catalog.
- Different characteristic curves matched to the appropriate
circuit. Refer to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87; System
Overview - Refrigerant Circuit (vehicle-specific
repair manual) and the Parts Catalog.
- 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.
Expansion Valve with Shut-Off Valve
Note
There are different versions of the shut-off valve with
different functions and with different names. The following
illustrated Hybrid Battery Refrigerant Shut-Off Valve 2 -N517-
is for example installed on an Audi Q7 hybrid in the battery
cooling module. Refer to
→ Heating, Ventilation and Air Conditioning; Rep.
Gr.87; Refrigerant Circuit; System Overview - Refrigerant
Circuit.
- The expansion valve -A- with
the Hybrid Battery Refrigerant Shut-Off Valve 2 -N517--B-
atomizes the streaming refrigerant and regulates the refrigerant
flow rate to the evaporator in the battery cooling module for
the Hybrid Battery Unit -AX1- so that the vapor becomes gaseous
only at the evaporator output, depending on the heat
transmission.
- If the Hybrid Battery Refrigerant Shut-Off Valve 2 -N517--B-
is activated by the electronics and is open, it lets refrigerant
flow through the expansion valve -A-
to the evaporator in the battery cooling module.
- The expansion valve -A- with
the Hybrid Battery Refrigerant Shut-Off Valve 2 -N517--B-
is installed on vehicles with a battery cooling module. It is
activated when the A/C system is in operation, if it is
necessary to cool the Hybrid Battery Unit -AX1-.
- If the Hybrid Battery Refrigerant Shut-Off Valve 2 -N517--B-
is activated by the electronics (for example, by the Battery
Regulation Control Module -J840-), it is open and lets the
refrigerant flow according to its control characteristic toward
the evaporator in the battery cooling module.
- The Hybrid Battery Refrigerant Shut-Off Valve 2 -N517--B-
attached to the expansion valve -A-
is activated, for example, by the Battery Regulation Control
Module -J840-. Refer to
→ Wiring diagrams, Troubleshooting & Component locations.
Use the Vehicle Diagnostic Tester in the "Guided Fault Finding"
Function for the A/C System and the Battery Regulation.
- If, for a vehicle with two evaporators (one in the A/C unit
and one in the battery cooling module, for example on the Q5
Hybrid), the measured temperature on one of the evaporators
corresponds to the specified value or the specified value falls
short, but does not reach the required specified value on the
other evaporator, the following adjustment is performed: the
Battery Regulation Control Module -J840- activates the electric
A/C compressor with increased speed (thereby increasing the A/C
system cooling output and decreasing the pressure on the low
pressure side as well as the evaporator temperature) via the
Electric Drive Power and Control Electronics -JX1- and the A/C
Compressor Control Module -J842-. If the specified value for the
temperature falls short at one of the evaporators, the Battery
Regulation Control Module -J840- activates the Hybrid Battery
Refrigerant Shut-Off Valve 1 -N516- or the Hybrid Battery
Refrigerant Shut-Off Valve 2 -N517-, so that the evaporator
which is too cold is no longer supplied with refrigerant. Use
the Vehicle Diagnostic Tester in the "Guided Fault Finding"
Function for the A/C System.
READ NEXT:
Note
There are different versions of the shut-off valve with
different functions and with different names. The following
illustrated Hybrid Battery Refrigerant Shut-Off Valve 1 -N516-
Refrigerant Circuit with Expansion Valve and Evaporator
The following illustration shows only the principle of a
refrigerant circuit, the design of the refrigerant circuit in
the respective vehic
General Information
Only valves and connections that are resistant to
refrigerant R134a and refrigerant oil must be installed.
Different connections (outer diameter) for high pressure and
lo
SEE MORE:
General information
Your vehicle is primarily intended for transporting
people and luggage. However, if you drive
with a trailer, follow the technical requirements,
the operation and driving tips, and the legal regulations.
Driving with a trailer affects the vehicle's energy
usage, performance, and
Applies to: vehicles with telephone
The business card shows you details about a contact.
To open a business card, press on a contact in
the directory, or
Press in the call list 5
fig. 125.
Possible options in the business card:
Call: press on a phone number.
Storing a favorite: press .