Before the worst of the hot weather fades blessedly into memory, let's give a good clap for the area's air-conditioning repairmen.

No one else contributes quite as much quite as quickly to our peace of mind. No one else works as hard to provide so much cool air to so many people.

And no one else puts up with so many emergencies that really aren't. For example, there was the call Roger Shrader got not long ago.

Shrader is the service manager for one of the area's largest air-conditioner sales and service companies. As Shrader recounted it to Frank Forrester of McLean, his home phone rang one impossibly hot weekend afternoon. On the other end was a woman who was obviously at the end of her rope.

"She was crying on the phone; said she simply had to have her conditioner repaired because 'her Leon' was having a heart attack and would die if the place wasn't cooled."

Shrader wondered why the woman hadn't arranged for an ambulance. But his job wasn't to run other people's lives. So he juggled and rejuggled the schedule to get a repairman out to Chez Leon right away.

"The repairman got to the house to find the tearful woman waiting anxiously for him," Forrester reports. "He went right to the conditioner and repaired it."

Only then did he ask about Leon.

Turns out he was a dog.

The Choice credit card bill was for $595.41, and David Kurtz doesn't know why he paid only $595. Maybe he didn't notice the 41 cents. Maybe he couldn't be bothered. Maybe he figured that running a balance of 41 cents wouldn't make any difference.

Believe me, it made a difference.

Under the Choice system, if you have a balance, regardless of how much, you pay a service charge the next month. But it's based not just on last month's balance, but on last month's balance plus this month's charges.

In David's case, that meant he paid a service charge on last month's 41 cents and on the entire $600 he ran up the next month. The total service charge was $6, which isn't much in the scheme of things. But if David had paid the 41 cents in the first place, he wouldn't have had to pay any service charges a month later.

By the way, the same billing policy holds true for Visa, American Express and every other major credit card. David's suggestion, based on bitter experience: Take care of the pennies, before they turn into dollars.