While driving her pre-owned 2007 Honda CR-V last summer, Odalys Grieco found hot air blowing from the vehicle's air conditioner.

With a broken air conditioner and what she thought was an expired warranty, she expected to pay a lot to have it repaired.

That was before she did some digging and discovered that there had been a problem with the air conditioning units in that model year, so she asked Honda about it and the company performed the repair for free.

"It would have cost me approximately $800 or more," she said.

Grieco's vehicle had what some call a "secret warranty," and Consumer Reports magazine has found hundreds of what it calls "hidden warranties."

"A lot of people think that their car's warranty is over and they're done. And in many cases that's not the case," the magazine's Jake Fisher told "GMA Investigates."

Car companies dispute calling the warranties "secret" or "hidden." Across the industry, car manufacturers call them "customer satisfaction campaigns" because they say that, when they discover a problem, they notify the dealer and the original owner.

Honda says it did that, but second owners, such as Grieco, don't necessarily get those notices.

John Holmes discovered the so-called "secret warranty" for a fuel pump on his pre-owned 2004 BMW 325i, saving himself $8,000.

"I felt like I won the lottery," Holmes said.

Honda and BMW told "GMA Investigates" that they are happy the customers received the free repairs.

So how can people find out whether their vehicles are covered by these types of warranties?

First, call the dealership and provide the year, make and model of your vehicle. Ask about any potential service campaigns or customer satisfaction campaigns that cover the problem your vehicle may be having. And don't forget to ask about any technical service bulletins on your vehicle.