I have 2 Ducane a/c units. They are 8 years old. I hardly ever use a/c, so I would estimate that I have used them less than 25 days total in 8 years. One of the units wasn't cooling, and an HVAC tech told me that the compressor is blown, and that I need a new one. I was floored. I told him I have used it so few times. The tech said he went over it completely, and that sometimes this "just happens". Should I get a second opinion?