However, you cannot deduct any expenses related to the renters. If you rented it to someone who put a hole in a wall, or ruined your plumbing, you could not deduct the cost of fixing it. At the other extreme is rental property - vacation property with minimal personal use. You can not deduct the mortgage interest for the time you spent there since the IRS figures your purpose for being there was to do repairs and maintenance in order to keep it up as viable rental property. But you can deduct your costs in the same way any landlord can.
Many people fit somewhere in the middle.
They use it for part of the year, and then rent it out from time to time, but for more than 15 days a year. You can deduct your interest payments for the time you use it, but you have to treat it as rental property when it is rented, and pay taxes on the rent you receive. You should also go to a CPA or tax lawyer to figure out what to do about the times it is sitting there empty. The number of days you use it and the number of days it is rented out will play a major part in determining its status when it's empty. But even if you don't rent it out, you still might want to talk it all over with your tax preparer, CPA or tax attorney.