FORT WORTH (CBSDFW.COM) – The sizzling temperatures are keeping many North Texans inside, and air conditioning companies busy.

Reliant Air Conditioning in Tarrant County has received more than 1,500 calls this month for help.  That’s a 40 percent increase from a year ago.

Merrick Garza knows how it feels to be without A/C. She spent her seventh birthday with her grandmother Tuesday, but the celebration wasn’t nearly as cool as it would usually be.  “It was like 80 degrees in the house and the temperature was set on 74,” said Merrick’s grandmother, Treva Downs.

The family’s air conditioning went out early Tuesday morning.  It’s a common problem right now said Jeff Stewart at Reliant Air Conditioning.

“Most people, they cringe at the high temperatures, but we in the industry look at the low temperature,” Stewart explained, “because when you don’t break 80 at night, the units, they have no chance to rest, they’re running constantly and that’s when you start to see mechanical failure.”

The average cost of an A/C repair is $235.

There are ways to keep the unit from running constantly. By closing blinds or curtains, leaving ceiling fans on, and not using major appliances like the oven or dishwasher during the heat of the day, you can help keep your house cooler.

Stewart also recommends changing your filter at least once a month.  “There’s definitely things you can do to reduce the load but we recommend preventative maintenance… Obviously, having your unit maintained, preventative maintenance can catch a problem before it becomes a big problem.”

But Merrick has her own words of wisdom on how to beat the heat. “Usually I go swimming or go somewhere where it’s cool.”