One reason that the heater will not work in an Audi A4 is that the fuse is blown. Another issue could be a short circuit in the wiring.
Please look below in the related links section for a detailed how-to.
A fuel pump pressure test could determine that.
Low coolant? Bad thermostat. Heater control cable most likely to be blocked heater core if blowing cold air! back flush heater pipes if this doesn't work heater core is a bad job to replace. dash out!
the ignition switch pull back the key toward you a little its been recalled by factory
The Blower Motor is located behind the glove box. It's really easy. You take out the glove box and there are three screws holding the blower motor on.
the answer is ricky bobby
at the compresser
If it is the same as a 2000 A4 then you have to replace the rotors with the pads so figure $500 per axle.
behind timing belt very$$$$$
Please look below in the related links section for a detailed how-to.
folding boxes and working witth A4 sheets of paper
Have a pro go at it, PITA to replace.