Heater Core: Service and Repair

Heater Core, Removing And Installing

Special tools and equipment
- Hose clamps 3093 or 3094
- Compressed air gun, standard
- V.A.G 1274 hand pump with adapters

CAUTION: On vehicles equipped with Audi Telematics by OnStar, switch-off the emergency (backup) battery for the Telematic/Telephone Control Module prior to disconnecting the vehicle battery. Switch-on the emergency (back-up) battery after reconnecting the vehicle battery.

Removing
- Remove plenum cover.
- Disconnect battery and remove.

NOTE:
- Obtain radio code before disconnecting battery.
- On vehicles with power seats, move the seats back as far as possible before disconnecting the battery.

- Release pressure in coolant system by opening cap on coolant expansion tank.







- Mark allocation of the coolant hoses -A- and -B-.
- Clamp off and disconnect both coolant hoses leading to heater core in air conditioner unit (e.g. using V.A.G 3094)

NOTE:
- The coolant hoses must be re-installed in the correct positions:
- Coolant hose -A- supply from cylinder head.
- Coolant hose -B- return to water pump.
- Bleed cooling circuit







- Place container under connection -A-.
- Place a piece of hose on connection -B- and carefully blow out coolant from heater core with compressed air.
- Remove grommet -C-.
- Remove driver side storage compartment.
- Remove accelerator pedal module.







- Remove screws -A- and remove cover -B- from coolant lines.
- Cover carpet beneath heater core connection with absorbent paper.







- Loosen clamps -A- and pull out both coolant lines -B- and -C- from heater core connections.
- Pull heater core -D- out of air conditioner.

Installing
- With the heater core removed, check air conditioner for soiling (via heater core opening).
- If necessary remove dirt or coolant from air conditioner unit (for example after removing leaky heater core).







- Check seals -A-, -B- and -C- on heater core, only install heater core with good seals.







- Lubricate new seals -A- slightly with coolant.
- Install new seals -A- (included in delivery) on the heater core connections -B-.
- Push heater core -C- into the air conditioner unit.







- Remove old clamps -A- from both coolant lines -B- and -C-.
- Install new clamps -A- (included in delivery) on both coolant lines for heater core according to illustration.
- Push both coolant lines -B- and -C- into heater core flange openings -D-.
- Check seating of seals between coolant lines and heater core again.







- Tighten both coolant lines -B-and -C-with clamps -A- on heater core.
- Check seating of both clamps -A-, clamps must enclose the flange on heater core and coolant line completely and should not touch other components.
- Tighten bolts on clamps -A- to 2.5 Nm.







- Connect coolant hoses properly to heater core. Observe markings:
A - supply hose from cylinder head
B - return hose to water pump
- Install removed components, except storage compartment driver's side, in reverse order.
- Bleed coolant circuit:


NOTE: The heater core must additionally be bled due to the allocation of the coolant lines to the heater core. Use following procedure to bleed cooling system.


- Bleed coolant circuit.
- Switch ignition off.
- Carefully open coolant reservoir cap (observe safety precautions when opening the cap)







- Loosen clamp on coolant hose -B-.
- Pull hose -B-back until the hole in the coolant hose is no longer sealed with the pipe.
- Increase pressure in coolant circuit e.g. using V.A.G1274 hand pump.
- Bleed heater core via coolant hose -B-until coolant exits bubble free.
- Push coolant hose -B-on heater core pipe and tighten with clamp.
- Add coolant if necessary.







- Check coolant circuit for leaks, pay particular attention between coolant hoses and heater core.
- Install driver's side storage compartment and other removed components.