Replacing a Volkswagen Passat's heater core is a very arduous process, although can be done by an experienced auto mechanic. As with any Volkswagen, the process will be difficult and time-consuming, so plan to spend several hours on this. These steps will, however, make sure you know you are on the right track to removing the core.
Disconnecting your Car
Before anything, disconnect the battery from the car and drain the coolant and refrigerant from the car. After the removal of these components, disconnect the hoses running into the heater core from the engine bay so that it can be easily removed from the inside of the car.
Taking Apart the Dash
To reach the heater core, you will need to disassemble the entire dashboard--including the instrument panel, the centre console, the radio and the glove box. Disconnect all of the electrical inputs to these elements so that you will have easier access behind the dash, where the heater core resides. Pull out the vents--the lines running to the vents will lead back just behind the dash to where the heater core is.
The heater core will have a few bolts holding it to the vents and the car that will need to be removed. Two of the bolts will be along the firewall, which is the wall between the engine bay and the inside of the car, while the rest will be inside the car. After removing the bolts, you will be free to disconnect the heater core from the car.