Should I have to pay maintenance fees while condo was close?

What is the name of your state (only U.S. law)? FL

I purchase a few units in 2006. I made an agreement with a management company that was base on the property to help me managed the property. They facilitate with renting the units and any maintenance that was needed for one year. I paid all my maintenance fees upfront and before the due date. The property management board when through some changes and the new members decided to shut down operation. I continue paying my maintenance fees for three months after and decided to stop since the units were not brining in any income. It became very challenging to continue paying for these units when I’m getting nothing out of them. The board of directors of the association are now pressuring me to pay all the past months, plus late payment, interest and whatever other expense they can think of. According to them my outstanding total is $15K. How is this possible to have to pay maintenance fee (that should have cover electricity, water, sewer, cable and common area expense) when the business was close?

You can't solve this type of problem on a forum. You have 3 problems.
1)Should you pay them?
2)How do you limit future costs, do you also owe on mortgages?
3)Can you recoup any of your investment? Do you have a cause of action against anyone?
I would urge you to attend some RE investment groups in your area. Ask the members for advice. Also ask for recommendations on a good real estate attorney. Only listen to the more experienced players.Then try to get a free consultation or pay for an hour's time.