Colen Thomas and his wife thought they were getting a great deal on a new air conditioner unit in their Tavares home.

[WEB EXTRA: Check your repairman's license app for iPhone | Android ]

Thomas said the $3,000 price he was given by Terry Adams "sounded pretty good to me."

So Thomas hired Adams and paid him up front to do the work. But after his new AC unit was installed, it wasn't working right. The system needed more parts, including a shroud, to be installed, Thomas said.

Thomas said Adams told him he'd come back to finish the job, but "he never came back."

"I kept calling him to come back and do it. And he kept putting me off from one place to another and finally he quit returning my calls," Thomas said.

That's when Thomas reported him and discovered Adams had no state license.

Adams was arrested on charges of contracting without a license, and Thomas had to hire a new, licensed contractor to "pull the unit and reinstall it," according to invoices Thomas shared with Local 6.

That cost Thomas an extra $650. It's a problem state officials see all the time, and they're constantly fighting to stop it.

"Because you're having someone work on probably the biggest investment of your life -- financial investment of your life --  and you want to make sure the people doing the work on that investment, on that property, have the knowledge and experience to do it right," said Tim McGrath, who works to catch unlicensed contractors.

McGrath works for Florida's Department of Business and Professional Regulation, which reports ordering 119 unlicensed contractors to stop performing work in Central Florida within about the last 10 months.

But sometimes contractors ignore those orders.

Peterson Germain of Orlando-based Island Air Systems Inc. has a suspended license, according to state records. But when Local 6's Eryka Washington confronted him about driving his work van around anyway, he denied he was unlicensed.

"I'm a licensed contractor," Germain said, pointing to the suspended license number on his work van.

"Are you telling people that you work for that it is suspended?" Washington asked.

But Germain refused to answer the question, saying, "I have nothing else to say to you."

The state DBPR also sets up stings, where they work with local law enforcement to lure unlicensed contractors advertising to do work to a house with undercover officers.  

During a recent sting conducted along with the Polk County Sheriff's Office, four people from the Kissimmee area were arrested after saying they'd perform unlicensed work.

Others get arrested after a complaint is filed. Richard Cudjoe is accused of installing a unit where "wiring in the home could not handle the load and could have possibly burned down the home," according to a construction complaint form Thomas M. Phillips filed with Orange County.

An investigation resulted in him being arrested and charged with unlawful contracting, grand theft and fraudulent use of personal information, for allegedly using a legitimate license number from another business as his own.

Cudjoe declined to be interviewed on camera Monday, but told Local 6 by phone that there is more to the story and that he's fighting the charges in court.

Another reason to avoid unlicensed contractors is because there's a good chance your homeowners insurance may not that work, officials said.

McGrath encourages anyone who is a victim of unlicensed contracting to report it. DBPR has a mobile app that allows you to verify the license right from your smart phone, and even submit a complaint, with photo evidence.

"The last thing we want to see is consumers to be taken advantage of, McGrath said. "We don't want to see people paying double to get work done."