My brother just had a house built and I noticed there is no filter/drier on his ac. It is a brand new install. I brought this up to the general contractor and he told me it is not required on new installs. Assuming (and I know this is a big assumption) the lines were nitrogen purged while brazing and evacuated below 50 microns, this shouldn't be a big deal. However, I seem to recall manufacturers requiring their installation on new units. Couldn't find any requirement in the IMC. Anyone know if there is a code requirement or manufacturer requirement for a Filter/drier.