Fan does a 1998 318.1 bmw have a a/c filter

On certain 3 BMW's (E36), the A/c filter (polymer filter) is situated inside the car at the Rh side of the centre console (loosen the cover on Rh side) and look at the rear of the ventbox (engine side) is a vertical panel that clips loose and the filter is slided into a holder behind it. Suggest useing a torch as it is very difficult to see if you do not know where to look for it. On some year models the filter is situated in the engine compartment below windscreen. Hope this can shed light on your problem

Some due there called fire wall filter
after a certain year they started placeing these kind of filters in vehicles
the year they started this leeps my mind but bmw and mercedis and jaguar were the leaders in new technology way ahead of time so its quite possible that your car has it