Heater Core, Removing And Installing: Installing

Install in reverse order of removal. Note the following:

-- Depending on the A/C system and vehicle version, cover the heater core with the foam seals provided -A- through -D-.

Fig 1: Depending On A/C Version, Cover Heat Exchanger With Foam Seal Provided

Courtesy of AUDI OF AMERICA, LLC

1 - Heater core for a vehicle equipped with a "Basis" A/C system.

2 - Heater core for a vehicle equipped with a "Convenience" A/C system.

3 - Ignore item -3-.

-- Check the seals on the heater core; only install a heater core with seals that are not damaged and are secured glued on.

NOTE:

If the vehicle has the "Convenience" A/C system, then there are different temperature settings for the right and left sides as well as for the rear. The seals -C- and -D- separate the air guides in the A/C unit from each other. Refer to AIR INTAKE AND OUTLET OPENINGS .

The heater core has a color mark that shows where to affix the seal -C-. The seal -D- must be applied to the center of the heater core as illustrated.

The seal -C- may have different lengths (a short version as illustrated or a long version which reaches all the way around the heater core). If the heater core is delivered with the longer seal -C-, then attach it all the way around the heater core.

Seal may curl up on insertion if not correctly bonded on.

If the seal is damaged or installed incorrectly, cold air can flow over the heater core; on vehicles equipped with the "Convenience" A/C system, it is possible that there is no clear separation between the various areas.

-- Check the A/C unit and the evaporator -F- with the heater core removed -A- (via heater core opening) for dirt.

Fig 2: Removing Heat Exchanger

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-- Remove any dirt or coolant which has leaked out of the A/C unit (for example, after removing a leaking heater core).

-- Check both connections -A- and -B- on the heater core -C- for damage and dirt.

Fig 3: Checking Both Connections Of Heat Exchanger For Damage And Dirt

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-- Grease both connections -A- and -B- on the heater core -C- with silicone grease.

NOTE:

The silicone grease part number is G 000 405 A2 .

This illustration shows the connection area of a heater core installed as a replacement part.

If the heater core installed by the manufacturer is to be reused (for example, after replacing the evaporator with the evaporator housing with the A/C unit removed), both O-rings -B- and both clips for the coolant pipes -F- are to be replaced. Install the coolant pipes -A- with the O-rings -B- and the clips for the coolant pipes -F- in the heater core. Refer to EVAPORATOR HOUSING, REMOVING AND INSTALLING (Evaporator housing, removing and installing).

Fig 4: Identifying Heater Core Connections

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-- Lightly moisten the seals -D- (contained in the heater core delivery) with coolant (or lightly with silicone grease).

Fig 5: Installing Coolant Pipes With Seals Into Heat Exchanger

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NOTE:

This and the following illustrations show the connection area and the installation of coolant pipes with a heater core installed as a replacement part.

-- Install the new seals -D- on both heater core coolant pipes -E- and -F-.

-- Push the heater core -A- into the A/C unit.

Fig 6: Supporting Heat Exchanger With A Plastic Wedge On Center Tunnel

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-- Support the heater core -A-, for example, with a plastic wedge -B- on the center tunnel -C- so that it cannot slip down when attaching the coolant pipes.

-- Install a longer screw -G- (with a M5 thread) all the way to the stop in the bracket -C- as shown in the illustration.

Fig 7: Installing Coolant Pipes With Seals Into Heat Exchanger

Courtesy of AUDI OF AMERICA, LLC

-- Install and push both coolant pipes -E- and -F- with each seal -D- into the heater core connection flange all the way. -H-.

CAUTION:

Risk of leaks at the heater core.

Squeezed O-ring seals, sharp-edged or coolant pipes/clamps that have not been inserted completely may lead to leaks.

NOTE:

Do not bend the coolant pipes -D- and -E- when pushing them into the connections on the heater core.

Fig 8: Ensure Seals Between Coolant Pipes Fit Securely

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-- Make sure the seals -C- between the coolant pipes -D- and -E- and the connections in the flange connection -B- of the heater core -A- fit securely.

CAUTION:

Seals that are incorrectly installed or jammed -C- will leak.

The seals -C- must be installed completely into both the coolant pipe connections -D- and -E- and the flange connections -B-.

-- Secure both coolant pipes -E- and -F- with the bracket -C- on the heater core flange -H-.

Fig 9: Installing Coolant Pipes With Seals Into Heat Exchanger

Courtesy of AUDI OF AMERICA, LLC

NOTE:

The screw -G- is used to help with the installation and must be removed after the bracket is installed.

-- Insert the screw -A- and the washer -B- and tighten the screw -A-.

Screw tightening specification -A- 2.5 Nm.

-- Remove the screw -G-.

-- Make sure the grommet -H- fits correctly in the back of the plenum chamber.

Fig 10: Identifying Battery (+) Cable, Coolant Hoses And Plenum Chamber Grommet

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-- Properly connect the coolant hoses to the heater core, pay attention to the marking.

A - Supply hose from cylinder head

B - Return to the coolant pump

-- Connect the coolant hose -A- to the heater core coolant pipe (pay attention to the marking) and secure it with the clamp -D-.

-- Attach the coolant hose to the heater core -B- onto the coolant pipe -F- just far enough as to not cover the bleed hole -G-.

-- Remove the hose clamp from the coolant hose -A-.

-- Fill the coolant expansion tank with coolant. Refer to FILLING for CALB, FILLING for CPNB, FILLING for CTUC and CTUD, FILLING for CAEB, CPMB, CPMA, or FILLING for CHJA .

-- Carefully force the coolant out of the coolant overflow reservoir into the heater core using, for example, the hand pump from the Cooling System Tester VAG1274B.

-- As soon as the coolant comes out the ventilation hole -G-, install the coolant hose -B- on to the coolant pipe -F- at the marking.

-- Secure the coolant hose -B- with the clamp -E- on the marked location.

-- Remove the hose clamp from the coolant hose -D-.

-- Add more coolant to the coolant reservoir, if necessary. Refer to FILLING for CALB, FILLING for CPNB, FILLING for CTUC and CTUD, FILLING for CAEB, CPMB, CPMA, or FILLING for CHJA .

NOTE:

This procedure completely bleeds the cooling system. If, for some other reason, there is still some air in the cooling system, install all removed components and bleed the system once again. Refer to FILLING for CALB, FILLING for CPNB, FILLING for CTUC and CTUD, FILLING for CAEB, CPMB, CPMA, or FILLING for CHJA .

Note: bleeding may be a part of "Coolant Mixture Ratio" in some draining and filling procedures.

Check the connections at the heater core for leaks as follows:

-- Carefully increase the pressure in the coolant circuit by using, for example, the hand pump of the Cooling System Tester VAG1274B.

-- Check the coolant circuit for leaks, paying special attention to the connection between the coolant pipes and the heater core. Refer to COOLING SYSTEM, CHECKING FOR LEAKS for CALD, COOLING SYSTEM, CHECKING FOR LEAKS for CPNB COOLING SYSTEM, CHECKING FOR LEAKS for CTUC and CTUD, or COOLING SYSTEM, CHECKING FOR LEAKS for CHJA, CAEB, CPMB, CPMA .

Fig 11: Identifying Replacement Heater Core With Bracket

Courtesy of AUDI OF AMERICA, LLC

NOTE:

When bleeding the coolant circuit, take special care to ensure complete bleeding of the heater core. If there are still air bubbles in the heater core, it may cause the customer to complain of insufficient heating output in winter or different air temperature from vents at same setting in regulated mode. Refer to A/C SYSTEM TEMPERATURE DOOR HEAT OUTPUT ACTIVATION, CHECKING .

Depending on vehicle equipment and on engine, heat insulation has been applied to coolant hoses, these must not be damaged and must be re-applied after installing.

-- Install all the components in reverse sequence. Refer to HEATER CORE, PREPARING FOR REMOVAL (Preparation work for removing the heater core).

On vehicles with a high voltage system (hybrid vehicles)

-- Attach the high voltage cables to the Electrical A/C Compressor -V470- and the Traction Battery -A2- to the Electric Drive Power and Control Electronics -JX1-. Refer to OVERVIEW - HIGH VOLTAGE CABLES .

-- Install the cowl panel trim -C-. Refer to PLENUM CHAMBER COVER, REMOVING AND INSTALLING .

-- Make sure the Electric Drive Power and Control Electronics -JX1- -D- and related wires -D- are installed correctly. Refer to HIGH VOLTAGE SYSTEM GENERAL WARNINGS .

Fig 12: Identifying Plenum Chamber Cover And High Voltage Components

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-- Energize the power supply to the high voltage system. Refer to HIGH VOLTAGE SYSTEM, RE-ENERGIZING , also see HIGH VOLTAGE SYSTEM GENERAL WARNINGS .

Restart the high voltage system

CAUTION:

Risk of electrocution

Death or serious bodily injury by electric shock

The high voltage system may only be restarted by qualified personal (Audi high voltage technicians).
Make sure the vehicle is energized using the "Guided Fault Finding " on the Vehicle Diagnostic Tester.
The qualified personal (Audi high voltage technician) restarts the vehicle.
The Audi high voltage technician should put a sign on the vehicle to identify it as a high voltage vehicle.

NOTE:

Restart the high voltage system:

Connect the vehicle diagnostic tester.

Select the Guided Fault Finding mode.

Using the GO TO button, select the following menu commands

Function/Component Selection

Body

Electrical Equipment

OBD-capable systems

8C - Battery Regulation Control Module -J840

8C - Battery Regulation Control Module, functions

51 - High voltage restart

For vehicles without a high voltage system

-- Reconnect the Battery -A- ground connection; when doing this, pay attention to the notes regarding reconnecting the battery. Refer to BATTERY, DISCONNECTING AND CONNECTING or Battery -A- AND Auxiliary Battery -A1-, DISCONNECTING AND CONNECTING, VEHICLES WITH HIGH VOLTAGE SYSTEM .

All vehicles

-- Turn on the ignition.

-- Perform a basic setting and the output diagnostic test mode for the A/C system using the Vehicle Diagnostic Tester in the "Guided Fault Finding " function.

NOTE:

On this vehicle, the actuators are equipped with electronics. During the basic setting, a new actuator learns its position on the A/C unit and can then be activated by the Climatronic Control Module -J255- A/C display and control head (currently all actuators are identical) using the Vehicle Diagnostic Tester in the "Guided Fault Finding " function.

During the basic setting, the actuators are assigned and adapted corresponding to the switching sequence of the wiring. If this sequence does not conform the specification, the adjustment motors will adapt incorrectly and the door control will be wrong. Refer to MAIN WIRING DIAGRAM FOR A/C SYSTEM ACTUATORS (A/C system actuators block diagram).

-- Turn on the ignition.

-- Check the DTC memory for the Climatronic Control Module -- A/C display and control head and erase any displayed malfunctions, if necessary using the Vehicle Diagnostic Tester in the "Guided Fault Finding " function.

-- Direct the airflow direction via the various settings on the Climatronic Control Module -J255- A/C display and control head to the different vents and check whether the air coming out at the vents actually changes according to the setting.