Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, post back with a clear picture of the top of the old AC adapter.
Still, the 12 VAC output is standard and therefore readily available. The 1500mA would be the minimum thus anything higher would also be acceptable; something like the product shown HERE.
Another factor to consider would be the type of plug that connects to the "...holiday inflatable..." hence the above picture request.