Preserving Multifamily Housing Act of 2014 - Prohibits the Director of the Federal Housing Finance Agency (FHFA) from taking any action that has the effect of reducing or limiting the volume or scope of the business of the Federal National Mortgage Association (Fannie Mae) or the Federal Home Loan Mortgage Corporation (Freddie Mac) (government-sponsored enterprises or GSEs) in mortgages for multifamily housing unless the Director: (1) determines that there is substantial evidence that such action is necessary to ensure the financial safety and soundness of the GSE, (2) causes that determination to be published in the Federal Register, and (3) submits written notice of the determination to Congress.