CHICAGO (CBS) — Residents of the Chatham neighborhood have been put on notice to keep an eye on their air conditioners.

Thieves have been sneaking into back yards and crawling onto rooftops to steal entire central air conditioning units.

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As CBS 2’s Kristyn Hartman learned, a rash of central air theft on the South Side prompted one neighborhood to put out a warning.

One Chatham resident, who asked to be identified only as “Randi” is using not one lock, but three, to protect her new air conditioner after thieves made off with her old one.

Asked if she ever thought someone would walk away with a central air unit, Randi said, “not in my wildest dreams.”

She said whoever stole the air conditioner was obviously very professional, because they didn’t leave any bolts or screws behind and she didn’t hear a thing.

“I’ve just been going door-to-door, letting my neighbors know, look, our air conditioner got stolen. At first, they’re like, ‘You all have central air, what do you mean your air conditioner got stolen?’” “My air conditioner got stolen. So they came by and they’re like, ‘How in the world did they do that? Everyone is in awe.”

She still isn’t certain exactly how they stole the whole thing.

Randi woke up one late June morning to a hot house. Her thermostat wasn’t registering. Out back, all she and her family found was an empty slab.

“We’re just jumping up and down, like, no, no,” she said.

Her warnings definitely helped.

When a neighbor checked on his unit, he found it prepped for theft.

“Two of his bolts were unscrewed and his Freon lines were cut,” Randi said.

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Turns out central air conditioning units are a hot commodity with thieves.

There’s word of a central air theft spree in the Chatham neighborhood on, a neighborhood news blog.

Chicago police said it’s an ongoing problem that’s affected the whole city for awhile now.

But Bernard Azrikam of The Price is Right Heating and Cooling said he’s seen a spike in such thefts of late.

“It’s happening a lot more than I’ve ever seen before … in three to six months,” he said.

Zzrikam believes it’s a sign of tough money times.

Theives who take the whole unit, which can weigh about 125 pounds, are looking to sell the copper and aluminum coil inside.

So Randi and some of her neighbors have cage protection now for their A/C units.

“I just can’t afford for someone to come and take it again,” Randi said.

Insurance covered some of the cost to replace the air conditioner, but the total cost of the cage and the new air conditioner was about $1,500 for Randi

And to think, our expert said the thieves only get about $25 for their haul.

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Professionals advise to lock up air conditioners and the disconnect box to make the unit harder to steal.