(WSBT) It's a sound we've been hearing a lot lately — air conditioners working overtime, as the August sun sends temperatures soaring.

Electric bills would be high anyway, but in Mishawaka a charge is adding to the sting.

Debra of Mishawaka wants to know, "what is the tracker charge on a utility bill?"

“It's too much, I just told you that,” one consumer said. “It's too much, but what am I going to do, complain to you?”

“It is high," another customer agreed. "Usually it's only about 29 or 35 and it's 55."

Mishawaka utility bills have what's called a residential tracker charge.

Mishawaka buys its electricity from Indiana Michigan Power. Last year the companies negotiated a new 26-year contract.

The tracker charge goes up when the cost of buying energy goes up.

“I think if you take a look at our electricity charges, they're commensurate with what's going on in the market place in terms of all energy costs,” Jim Schrader of GM Mishawaka Utilities said.

Schrader says the new contract with I&M only started showing tracker charge increases on bills this summer.

He estimates the average increase on bills will be 8%-10%.

The tracker charges are estimated over three month periods. The next quarter starts in October at that point you should notice a change in the charge. It will probably drop because the weather will have cooled down.