Second mortgage on residential real property?

[David Sicks]

15 years ago, I bought a residential property and lived in it for two years. Then I moved away and rented the residential property. I have paid down the original mortgage quite a bit. Can I take a second mortgage now to harvest some equity and put more interest expense on the annual rental property tax calculation?

If that is possible, I would appreciate a reference or references to information, rules, etc. that are related to that transaction.

Thanks.