HARRISBURG, S.D. (KELO) – This summer’s extended heat wave is keeping some workers busier than ever. For those in the AC repair business, phones are ringing nonstop.

Air conditioning is music to the ears of homeowners on a hot day.

But what happens when the AC music stops?

“Last night when we go to bed, we turned it down and it took a long, long time before it caught up again,” homeowner Gene Gillen said.

Fortunately, Hahne Heating and Air makes service calls to hot homeowners a priority.

“The phone has been ringing off the hook,” AC technician Adam Strong said.

Strong has been busy with service calls all summer.

“The big thing when it comes to air conditioning is airflow,” Strong said. “You want to make sure that your air filter indoors is clean.”

Gillen’s AC unit just needed a good flush.

“If it’s dirty and impacted with cottonwood seeds or leaves or whatever, it cannot breathe properly,” Strong said.

Meaning it can’t keep you cool. If you find yourself in a sweltering house, Strong has advice that might seem counterintuitive.

“The big thing is, turn it off. If we show up and it’s frozen, we can’t do anything with it until it thaws out,” Strong said.

That could take hours. Gillen says it’s well worth the money to make the phone call and cool down quickly.

“If you’re not comfortable, it’s miserable,” Gillen said.

The AC unit at this house was clear, but if it’s overgrown with plants of any kind, Strong says you should prune them back for better airflow.