Audi Q7: 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.
READ NEXT:
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 ar
In this refrigerant pipe, the flowing fluid warm refrigerant
on the high pressure side is delivered into the low pressure
side as flowing, vapor, cold refrigerant to increase the
efficiency of the
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 vehicle
SEE MORE:
Connection Diagram - Coolant Hoses
Connection Diagram - Coolant Hoses, Vehicles without Parking Heater
Note
Blue = large coolant circuit.
Red = small coolant circuit.
Orange = coolant circuit for the charge air cooler.
Brown = heating circuit.
Green = coolant circuit for the transmissi
Special tools and workshop equipment
required
Hose Clamps - Up To 25 mm -3094-
Engine Bung Set -VAS6122-
Container of the Coolant Collection System -VAS5014- or the
Shop Crane - Drip Tray -VAS6208-
Hose Clip Pliers -VAS6362-
Caution
This procedure contains mandatory replaceable part