ROCKVILLE, Md. — After a serious problem caused Montgomery County’s 911 system to shut down earlier this year, county leaders say they are in the process of making changes to ensure it does not happen again.

During the evening on July 10, an air conditioner malfunctioned at the county’s emergency communications center in Rockville. As a result, a power supply room overheated, reaching temperatures of 120 degrees. Emergency 911 calls could not get through to the center, and the system was down for over an hour.

“Hindsight is 20/20,” said David Dise, director of Montgomery County’s Department of General Services.

Dise told county council members at a hearing Monday morning that such an incident should not happen again because a new AC unit has been installed, with a backup system that would kick in if problems arise in the future.

“Clearly redundancy is appropriate,” Dise said. “Once the problem was exposed, certainly redundancy is what has been put in place now.”

In the wake of July’s incident, the county is still working on other improvements, including better maintenance and training for staff, more oversight and a stronger plan for dealing with potential system outages.

County officials are also identifying other changes that need to be made by inspecting 400 county facilities, a project that is expected to last three years.