Electric Cooling Fans — Audi A8 D3 (2002-2005)

ENGINE IDENTIFICATION

For A8 models with the 3.7L V8 or 4.2L V8 engine and Engine Codes AEW and ABZ the engine code letters and serial number are stamped on the left side of the cylinder block (arrow), directly above the power steering pump. (Scheme 1) In addition, an adhesive label with engine code letters and serial number is affixed to the toothed belt guard. The engine code letters are also listed on the vehicle data plate.

Scheme 1

Scheme 1: ENGINE IDENTIFICATION

For A8 models with the 4.2L V8 models with Engine Code AKB and AUX and S8 4.2L V8 models with Engine Code AYS, the engine code and serial numbers located on the left side of the cylinder block. (Scheme 2) The engine number is also listed on a label on the belt cover. The engine code is included on the vehicle data label.

Scheme 2

A/C HIGH PRESSURE COMBINATION SWITCH (F23 & F118)

Note. A/C High Pressure Combination Switch (F23 and F118) is used on 1997 models.

A/C pressure switch is a combination switch (two switching components) that protects refrigerant circuit components from malfunctioning due to excessive or insufficient refrigerant system pressures. Both switches are incorporated into a single housing. Function of F23 is to switch coolant fan V7 to second speed when A/C system pressure increases, (terminals 1 and 2). (Scheme 3) Function of F118 is to switch A/C clutch N25 off, if system pressure is too high, (terminals 3 and 4). (Scheme 3)

Scheme 3

Scheme 3: A/C HIGH PRESSURE COMBINATION SWITCH (F23 & F118)

A/C PRESSURE SWITCH (F129)

Note. A/C Pressure Switch (F129) is used from 1998 through 2003. On 1998 models the A/C Pressure Switch (F129) is used with the new A/C Control Head (E87). (Scheme 4)

A/C pressure switch is a combination switch (two switching components) that protects refrigerant circuit components from malfunctioning due to excessive or insufficient refrigerant system pressures. Switch part between terminals 1 and 2 switches off the A/C clutch when the system pressure is too high or when there is not enough refrigerant in the system. Switch part between terminals 3 and 4 switches coolant fan to second fan speed when system pressures increase. (Scheme 5)

Scheme 4

Scheme 4: A/C PRESSURE SWITCH (F129)

Scheme 5

COOLANT FAN CONTROL THERMO SWITCH

Coolant Fan Control Thermo Switch is a 2-stage thermo switch. Coolant Fan Control Thermo Switch signals the coolant fan first and second stage relays.

COOLANT FAN THIRD SPEED RELAY (J135)

Coolant Fan Third Speed Relay (J135) receives the activation signal from the Instrument Cluster Combination Processor (J218). See WIRING DIAGRAMS .

COMPONENT LOCATIONS

Component		Location
A/C High Pressure Combination Switch (F23 & F118, 1997)		Lower Left Side Of Engine Compartment. (Scheme 6)
A/C Pressure Switch, 1998 Through 2003		Lower Left Side Of Engine Compartment. (Scheme 6)
Climatronic (Auto A/C) Control Module, All Models		Integrated With A/C Control Panel
Climatronic (Auto A/C) Control Panel, 1998 & 1999		Above Center Console, In Dashboard. (Scheme 4)
Climatronic (Auto A/C) Control Panel, 2000 Through 2003		Above Center Console, In Dashboard.
Coolant Fan Control Series Resistor, All Models		Lower Left Side Of Engine Compartment. (Scheme 7)
Coolant Fan Ground Point, All Models		Left Lower A Pillar
Coolant Fan Thermo Switch, All Models		In Lower Right Corner, In Radiator (Scheme 8)
First Speed Coolant Fan Relay, 1997		In 10-Fold Auxiliary Relay Panel (Position No. 1). (Scheme 9)And (Scheme 10).
First Speed Coolant Fan Relay, 1998-2003		Above, To The Right Of Auxiliary Relay Panel, In Driver's Footwell. (Scheme 11)And (Scheme 12).
Second Speed Coolant Fan Control Relay, 1997		In 10-Fold Auxiliary Relay Panel (Position No. 2). (Scheme 10)
Second Speed Coolant Fan Control Relay, 1998-2003		Above, To The Right Of Auxiliary Relay Panel. (Scheme 12)
Third Speed Coolant Fan Control Relay, All Models		Above, To The Right Of Auxiliary Relay Panel. (Scheme 11)And (Scheme 13).
Passenger Compartment Fuse Panel & Coolant Fan Relay Fuses
Passenger Compartment Fuse Panel, All Models		Passenger Compartment Fuse Panel, Behind Cover In Passenger Footwell. (Scheme 14)
Activation Fuse For Coolant Fan Relay Coils, S4 (5 Amp)		Passenger Compartment Fuse Panel, Behind Cover In Passenger Footwell. (Scheme 14)And (Scheme 15).
Fuse For Coolant Fan Relays, (Coolant Fan Power), S42 (60 Amp)		Passenger Compartment Fuse Panel, Behind Cover In Passenger Footwell. (Scheme 14)And (Scheme 15).

COMPONENT LOCATIONS

Scheme 6

Scheme 7

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Scheme 14

Scheme 15

SYSTEM TESTS

System testing information is not available from manufacturer. To assist in circuit diagnosis, see WIRING DIAGRAMS . Ensure all fuses are okay before proceeding with any testing. If a fuse is blown, check for a short circuit and repair before replacing fuse.

COMPONENT TESTS

CAUTION

When working with electronics in the cooling system, be aware that all three speed coolant fan relays always have positive battery voltage (B+) and Cooling Fan has a permanent ground. Coolant Fan can start automatically.

Note. Switching element (F23) of A/C High Pressure Combination Switch (F23 and F118) is used for second fan speed relay activation.

Switch terminal Nos. 1 and 2 control coolant fan operation through the second fan speed relay. (Scheme 5)and WIRING DIAGRAMS. Fan speed increases to second speed when system pressure increases. Switch is closed from 207 psi (14.3 bar) up to 251 psi (17.3 bar). Second fan speed turns on and switch opens again from 158 psi (10.9 bar) up to 222 psi (15.3 bar). Second fan speed turns off. Pressure difference between switching points is 29 psi up to 49 psi (2.0 bar up to 3.4 bar).

Switch terminal Nos. 3 and 4 control coolant fan operation through the second fan speed relay. (Scheme 5)and WIRING DIAGRAMS. Fan speed increases to second speed when system pressure increases. Switch closes above 232 psi (16 bar). Second fan speed turns on and switch opens again below 181 psi (12.5 bar), when second fan speed turns off.

COOLANT FAN (V7)

There is no diagnostic information available from the manufacturer. See WIRING DIAGRAMS if wiring is suspect.

CAUTION

Note. There is no diagnostic or specification information available from the manufacturer. See WIRING DIAGRAMS if wiring is suspect.

TORQUE SPECIFICATIONS

When replacing A/C High Pressure Combination Switch (F23 and F118) or A/C Pressure Switch (F129), A/C refrigerant does not need to be discharged. Torque specifications is 44 INCH lbs. (5 N.m). Always install a new "O" ring.