The heater fan, a part of the heater box, is used to blow warm air into the car. For VW Caddys, this whole set-up will need to be pulled out to remove the heater fan. It is an intrusive job and not an easy one. If you have a great deal of experience working on your car, it might be something you are willing to tackle.
Drain the radiator out completely before you begin. You will find two hoses that run from the engine compartment to the heater core. Trace the lines to the inside of car and remove them. Be careful with the removal of these lines as the pipes they are connected to are fragile and, after years of use, it can be difficult to separate the two. Use a small screwdriver and work it between the two to create the separation. Because of the screws located behind it, remove the stereo. This is a simple task, but you will need a special radio removal hook to pull it from its place. Locate the two 8mm screws behind the radio and unscrew them. They will disconnect the heater box from the inside.
Above the accelerator of the car, there will be a set of white, brown and yellow wires. Disconnect these wires from their plug-in as they attach to the heater box. Beneath the bonnet, the heater box will be held in by four 8mm screws. Remove these four screws. Make sure to keep a small hold on the heater box so it does not rip out all the wiring in the car. With the heater box now disconnected, pull it from the car. There will be one 8mm screw which holds the fan onto the box. It would be impossible to get to this screw without complete removal, although it will pop right off once it is out of the car.