MANSFIELD – The work is constant for Just Chillin' Heating and Air. The homeowners are hot, and the air conditioners are over-worked and often too old.

"I always tell them, I always say, 'Well, you gotta try working outside all day, or being up in the attic,'" said James Shelley, a technician with the A/C repair company. "If you think this [is] hot – this ain't nothing."

James Shelley and his partner Bo are replacing the guts of an A/C unit in Mansfield. It's pushing 100 degrees in the shade, and it's about to heat up.

Believe it or not, the hottest part of their day isn't outside, its upstairs and in the attic. Before noon, the temperature is 103 and climbing.

"It is so hot up there most of the time that you can't breathe," Shelly said. "Attics get anywhere from 150-to-200 degrees."

It's work even the pros can only do 30-to-40 minutes at a time. Shelley's spent 16 years in the business, and in that time, he's learned that hydration is about more than health.

If the sun sidelines him, he's the one that pays for it.

"Most people cant afford to take off – y'know, a day or two days off work without pay," Shelly said. "You gotta stay hydrated, because it wears out your body."

With months of heat ahead of him, Shelley and his crew don't have time to let the sun keep them off the clock.