How do you remove and replace the heater core

Remove heater/air conditioner assembly. See Heater core case service and repair, Heater/Air conditioner, Servicing See: Heater Core Case Service and Repair. Also see Housing Assembly HVAC service and repair, Heater/Air conditioner, remove and install See: Housing Assembly HVAC Service and Repair Heater/Air Conditioner Assembly, Remove and Install
Press catches -A- and pull heater core from housing.
NOTE:
If the replacement heater core does not engage in the heater housing when installing, attach with 2, 3.2x20 mm screws -B-.
Apply self adhesive seal to heater core.

Heater/Air Conditioner Assembly, Removing and Installing

CAUTION!

Obtain security code for anti-theft radio.
Note customer's pre-set radio stations.
Move power seats to most rearward position.
Switch off ignition and disconnect battery ground (GND) strap.
Release pressure in coolant system by opening cap at coolant expansion tank.
WARNING!

With hot engine, cooling system is under pressure.
Coolant expansion tank cap must be removed slowly.
Dispose of used coolant properly. Check local regulations.
Do not re-use used coolant.

Clamp coolant hoses -A- and -B- with VAG3094 (or equivalent) and remove from heater core inlet/outlet.
Place catch basin below heater core connection -A- and carefully blow coolant out of heater core with compressed air through connection -B-.
Remove boot -C-.
CAUTION!
A/C refrigerant system must be discharged before removing heater/air conditioner assembly.

Discharge refrigerant system.

Remove bolt -A-.
Remove refrigerant lines from evaporator and secure with tie wraps to prevent interference during installation.
CAUTION!
Immediately plug open connections on A/C components and lines to prevent dirt and moisture contamination.

Plug evaporator openings using cap supplied with replacement evaporator -C-.
Remove bulkhead grommet -D-.
Remove glovebox
Remove driver side under-dash panel, center console and instrument panel outer skin

Remove instrument panel support -A-.
Loosen instrument panel support -B- (the upper mounting bolt to the heater/air conditioning assembly can not be removed).
Remove floor outlet.

Remove bolts -A-.
Disconnect all electrical connections from instrument panel harness to heater/air conditioner assembly.

Remove bolts -A-.
Remove heater/air conditioner assembly towards passenger side.
Install in reverse order of removal.
Notes on installation:
Replace all damaged heater/air conditioner assembly seals.
Replace all removed cable tie wraps in the same location.
Always replace evaporator inlet/outlet O-rings.
Ensure refrigerant lines fit into evaporator without binding.
Check evaporator line and heater core bulkhead grommets for correct fit.
Check evaporator drain and evaporator drain valve for correct fit.