Suffolk police are urging homeowners to be especially protective of their air-conditioning units.

A string of thefts of air-conditioning units has been ongoing throughout the city for the last few weeks. City spokeswoman Debbie George said such thefts are common, especially in warmer weather.

“Typically, when it’s this hot outside, we do see an increase,” she said. “It doesn’t seem like it’s more than usual.

What is unusual is that many of the recent thefts have been from homes that are unoccupied, either because they are under construction or because they are on the market, George said.

Police do not know if the thieves are stealing the units for resale or to strip the copper out of them for sale, George said. It’s also possible they are installing them on their own homes, although that is less likely, George said.

In the most recent incident, an air-conditioning unit was disconnected from a home under construction on Jackson Road, George said.

She recommended that owners of unoccupied homes ask their neighbors to keep an eye out for trespassers on the property.