Well, my wife's 2003 A4 1.8T developed a problem today. It started "fogging" the interior through the heat vents. The residue on the windows is slightly oily and smears around if you touch it with your fingers or hand. It does have a smell that is very similar to radiator fluid or kind of an "electrical hot" radiator fluid smell. I am assuming that the heater core has developed a leak.
I understand how heater cores work, so I don't need an explanation there. I have changed out cores on Jeeps of mine, but those are the most simple vehicles in the world. Does anyone know of a website or other links that will show step by step instructions for how to change the core myself?
Does anyone think that it is NOT the heater core? If so, let me know what you think it is.
Thanks and Merry Christmas!!
I understand how heater cores work, so I don't need an explanation there. I have changed out cores on Jeeps of mine, but those are the most simple vehicles in the world. Does anyone know of a website or other links that will show step by step instructions for how to change the core myself?
Does anyone think that it is NOT the heater core? If so, let me know what you think it is.
Thanks and Merry Christmas!!
1st Gear
it's the heater core and it requires the entire dash to be removed, not for the faint of heart.
I did it on my 98 a4, really don't want to do that again.
You would probably want a factory manual before attempting to perform the repair.
I did it on my 98 a4, really don't want to do that again.
You would probably want a factory manual before attempting to perform the repair.
RE: 2003 A4 1.8T Heater Core Issues
Removing and installing heating system heat exchanger[/align]Removing and installing heating system heat exchanger[/align]
Special tools, testers and other items required
◆Hose clamps 3093/3094
◆Commercially available compressed-air gun
◆Hand pump V.A.G 1274 (and appropriate adapters) [/ul]
Removing
‒Remove plenum chamber cover.
‒Disconnect and remove battery[/ul]
Notes:
◆If applicable, obtain radio anti-theft code before disconnecting battery.
◆On vehicles with electrically adjustable seats, move seats to rearmost position before disconnecting battery. [/ul]
‒Dissipate pressure in coolant circuit by opening cap at coolant expansion tank. [/ul]
=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
‒→ Mark positions of coolant hoses -A- and -B-.
‒Pinch off both coolant hoses to heating system heat exchanger (e.g. using V.A.G 3094) and detach hoses. [/ul]
Notes:
◆Take care to connect coolant hoses correctly:
‒Coolant hose A - supply from cylinder head
‒Coolant hose B - return to water pump [/ul]
◆Bleeding coolant circuit [/ul]
=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
‒→ Place vessel beneath connection -A-.
‒Attach piece of tubing to connection -B- and use compressed-air gun to carefully blow coolant out of heat exchanger (into vessel).
‒Remove grommet -C-. [/ul]
‒Remove driver's storage compartment. [/ul]
‒Remove accelerator pedal module. [/ul]
=> Relevant Fuel System Workshop Manual; Repair Group 20
‒→ Remove bolts -A- and detach cover -B- from coolant pipes.
‒Unplug connectors from additional heating heater element -Z35 (only applies to vehicles with diesel engine).
‒Use absorbent paper to cover carpet beneath connections to heat exchanger. [/ul]
‒→ Unfasten clips -A- and pull the two coolant pipes -B- and -C- out of heat exchanger connections.
‒Pull heat exchanger -D- out of heater. [/ul]
Installing
‒With heat exchanger removed, check for contamination of heater (by way of heat exchanger duct).
‒Remove any dirt or remnants of escaped coolant from heater (e.g. after removing leaking heat exchanger).
‒→ Check seals -A-, -B- and -C- attached to heat exchanger. Only install heat exchangers with intact seals. [/ul]
‒→ Slightly moisten new seals -A- with coolant.
‒Insert the new seals -A- (included in scope of delivery of heat exchanger) into connections of heat exchanger -B-.
‒Slide heat exchanger -C- into heater. [/ul]
‒→ Remove old clips -A- from both coolant pipes -B- and -C-.
‒Attach new clips -A- (included in scope of delivery of heat exchanger) to both heat exchanger coolant pipes as shown.
‒Press the two coolant pipes -B- and -C- into connections of heat exchanger -D-.
‒Re-check position of seals between coolant pipes and heat exchanger. [/ul]
‒→ Attach the two coolant pipes -B- and -C- with clips -A- to heat exchanger.
‒Check position of both clips -A-. They must completely surround flange at heat exchanger and coolant pipe and not make contact with other components.
‒Tighten bolts at clips -A- to 2.5 Nm. [/ul]
‒→ Connect coolant hoses to heat exchanger in proper manner, paying attention to markings: [/ul]
A -Supply from cylinder head
B -Return to water pump [/ul]
‒Re-install components removed (with the exception of driver's storage compartment) in reverse order.
‒Bleed coolant circuit. [/ul]
=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
Note:
Heat exchanger also has to be bled on account of layout of coolant pipes to heating system heat exchanger. Proceed as follows:
‒Bleed coolant circuit.
‒Switch off ignition.
‒Carefully open cap at coolant expansion tank (heed relevant safety precautions). [/ul]
=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
‒→ Unfasten clip at coolant hose -B-.
‒Push back hose -B- such that hole in hose is no longer covered by pipe.
‒Use hand pump V.A.G 1274, for example, to increase pressure in coolant circuit.
‒Bleed heat exchanger by way of hose -B- until there are no bubbles in coolant emerging.
‒Slip on coolant hose -B- and secure it with clip.
‒Top up coolant if necessary. [/ul]
‒→ Check coolant circuit for leaks, paying particular attention to connection between coolant pipes and heat exchanger. [/ul]
=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
‒Re-install driver's storage compartment and remaining components removed.[/ul]
pictures to follow
Removing and installing heating system heat exchanger[/align]Removing and installing heating system heat exchanger[/align]
Special tools, testers and other items required
◆Hose clamps 3093/3094
◆Commercially available compressed-air gun
◆Hand pump V.A.G 1274 (and appropriate adapters) [/ul]
Removing
‒Remove plenum chamber cover.
‒Disconnect and remove battery[/ul]
Notes:
◆If applicable, obtain radio anti-theft code before disconnecting battery.
◆On vehicles with electrically adjustable seats, move seats to rearmost position before disconnecting battery. [/ul]
‒Dissipate pressure in coolant circuit by opening cap at coolant expansion tank. [/ul]
=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
‒→ Mark positions of coolant hoses -A- and -B-.
‒Pinch off both coolant hoses to heating system heat exchanger (e.g. using V.A.G 3094) and detach hoses. [/ul]
Notes:
◆Take care to connect coolant hoses correctly:
‒Coolant hose A - supply from cylinder head
‒Coolant hose B - return to water pump [/ul]
◆Bleeding coolant circuit [/ul]
=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
‒→ Place vessel beneath connection -A-.
‒Attach piece of tubing to connection -B- and use compressed-air gun to carefully blow coolant out of heat exchanger (into vessel).
‒Remove grommet -C-. [/ul]
‒Remove driver's storage compartment. [/ul]
‒Remove accelerator pedal module. [/ul]
=> Relevant Fuel System Workshop Manual; Repair Group 20
‒→ Remove bolts -A- and detach cover -B- from coolant pipes.
‒Unplug connectors from additional heating heater element -Z35 (only applies to vehicles with diesel engine).
‒Use absorbent paper to cover carpet beneath connections to heat exchanger. [/ul]
‒→ Unfasten clips -A- and pull the two coolant pipes -B- and -C- out of heat exchanger connections.
‒Pull heat exchanger -D- out of heater. [/ul]
Installing
‒With heat exchanger removed, check for contamination of heater (by way of heat exchanger duct).
‒Remove any dirt or remnants of escaped coolant from heater (e.g. after removing leaking heat exchanger).
‒→ Check seals -A-, -B- and -C- attached to heat exchanger. Only install heat exchangers with intact seals. [/ul]
‒→ Slightly moisten new seals -A- with coolant.
‒Insert the new seals -A- (included in scope of delivery of heat exchanger) into connections of heat exchanger -B-.
‒Slide heat exchanger -C- into heater. [/ul]
‒→ Remove old clips -A- from both coolant pipes -B- and -C-.
‒Attach new clips -A- (included in scope of delivery of heat exchanger) to both heat exchanger coolant pipes as shown.
‒Press the two coolant pipes -B- and -C- into connections of heat exchanger -D-.
‒Re-check position of seals between coolant pipes and heat exchanger. [/ul]
‒→ Attach the two coolant pipes -B- and -C- with clips -A- to heat exchanger.
‒Check position of both clips -A-. They must completely surround flange at heat exchanger and coolant pipe and not make contact with other components.
‒Tighten bolts at clips -A- to 2.5 Nm. [/ul]
‒→ Connect coolant hoses to heat exchanger in proper manner, paying attention to markings: [/ul]
A -Supply from cylinder head
B -Return to water pump [/ul]
‒Re-install components removed (with the exception of driver's storage compartment) in reverse order.
‒Bleed coolant circuit. [/ul]
=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
Note:
Heat exchanger also has to be bled on account of layout of coolant pipes to heating system heat exchanger. Proceed as follows:
‒Bleed coolant circuit.
‒Switch off ignition.
‒Carefully open cap at coolant expansion tank (heed relevant safety precautions). [/ul]
=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
‒→ Unfasten clip at coolant hose -B-.
‒Push back hose -B- such that hole in hose is no longer covered by pipe.
‒Use hand pump V.A.G 1274, for example, to increase pressure in coolant circuit.
‒Bleed heat exchanger by way of hose -B- until there are no bubbles in coolant emerging.
‒Slip on coolant hose -B- and secure it with clip.
‒Top up coolant if necessary. [/ul]
‒→ Check coolant circuit for leaks, paying particular attention to connection between coolant pipes and heat exchanger. [/ul]
=> Relevant Engine, Mechanics Workshop Manual; Repair Group 19
‒Re-install driver's storage compartment and remaining components removed.[/ul]
pictures to follow
RE: 2003 A4 1.8T Heater Core Issues
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RE: 2003 A4 1.8T Heater Core Issues
Checking heat output[/align]Note on vehicles with auxiliary heater (poor heat output)[/align]
If complaints are received about poor or inadequate heat output at low engine speeds on vehicles fitted with an auxiliary heater as optional extra, check actuation of auxiliary heater recirculating pump -V55 by additional heater control unit -J364.
◆Actuation of the recirculating pump -V55 increases the flow of coolant through the heating system heat exchanger at low engine speeds and thus improves heat output.
◆The additional heater control unit -J364 switches on the recirculating pump -V55 if it receives the following information via the convenience data bus: [/ul]
‒Ignition on and engine running
‒Ambient temperature less than 20 °C
‒Engine speed less than 2000 rpm
‒Operating and display unit for air conditioner/Climatronic -E87 switched on ("OFF button" not pressed) [/ul]
‒At least one of the two temperature flaps not on "cold" stop [/ul]
◆Recirculating pump -V55 is switched on as soon as all cut-in conditions are met. To stop recirculating pump being constantly switched off and on, it remains activated for at least 30 s even if - for example in the event of rapid changes in vehicle speed - a request is only applied for several seconds (e.g. on accelerating after standing at traffic lights).
◆Incorporation of auxiliary heater (and recirculating pump -V55) into coolant circuit is described in [/ul]
◆If vehicles with auxiliary heater and petrol engine are fitted with an operating and display unit for air conditioner/Climatronic -E87 with a hardware/software version as of "XX15" (index "D" onwards), they must not be equipped with an auxiliary heater control unit (additional heater control unit -J364) with hardware/software version "XX09". Such a combination can lead to problems with actuation of recirculating pump -V55 when engine is running. This problem is no longer encountered with additional heater control units -J364 as of hardware/software version "XX10". [/ul]
◆As of Model Year 2003, operating and display units for air conditioner/Climatronic -E87 with part number as of index "D" (with hardware/software version as of "XX15") are gradually being introduced. With this -E87 version, the passenger compartment temperature regulation is designed to be somewhat cooler. [/ul]
=> Parts List
◆Vehicles with 4-cyl. petrol direct injection engine (FSI) are only to be fitted with operating and display units for air conditioner/Climatronic -E87 with part number as of index "D". [/ul]
If complaints are received about poor or inadequate heat output at low engine speeds on vehicles fitted with an auxiliary heater as optional extra, check actuation of auxiliary heater recirculating pump -V55 by additional heater control unit -J364.
◆Actuation of the recirculating pump -V55 increases the flow of coolant through the heating system heat exchanger at low engine speeds and thus improves heat output.
◆The additional heater control unit -J364 switches on the recirculating pump -V55 if it receives the following information via the convenience data bus: [/ul]
‒Ignition on and engine running
‒Ambient temperature less than 20 °C
‒Engine speed less than 2000 rpm
‒Operating and display unit for air conditioner/Climatronic -E87 switched on ("OFF button" not pressed) [/ul]
‒At least one of the two temperature flaps not on "cold" stop [/ul]
◆Recirculating pump -V55 is switched on as soon as all cut-in conditions are met. To stop recirculating pump being constantly switched off and on, it remains activated for at least 30 s even if - for example in the event of rapid changes in vehicle speed - a request is only applied for several seconds (e.g. on accelerating after standing at traffic lights).
◆Incorporation of auxiliary heater (and recirculating pump -V55) into coolant circuit is described in [/ul]
◆If vehicles with auxiliary heater and petrol engine are fitted with an operating and display unit for air conditioner/Climatronic -E87 with a hardware/software version as of "XX15" (index "D" onwards), they must not be equipped with an auxiliary heater control unit (additional heater control unit -J364) with hardware/software version "XX09". Such a combination can lead to problems with actuation of recirculating pump -V55 when engine is running. This problem is no longer encountered with additional heater control units -J364 as of hardware/software version "XX10". [/ul]
◆As of Model Year 2003, operating and display units for air conditioner/Climatronic -E87 with part number as of index "D" (with hardware/software version as of "XX15") are gradually being introduced. With this -E87 version, the passenger compartment temperature regulation is designed to be somewhat cooler. [/ul]
=> Parts List
◆Vehicles with 4-cyl. petrol direct injection engine (FSI) are only to be fitted with operating and display units for air conditioner/Climatronic -E87 with part number as of index "D". [/ul]