What if your handyman / contractor damages tenants' belongings?

[Nicole A.]

What would you do?

There is a handyman working on the exterior of the rental and he's doing some repointing brick work. The renters have a new (according to them) window unit AC and the contractors have let mortar drop on top of the unit and dry. They say that dust and debris from grinding out the joints also got in/on the AC unit and some fins were bent.

The tenants ask me why the guy didn't cover the AC unit or ask them to remove it from the window.

They did not say that it's broken, so I assume it's working. What would I, the landlord, be responsible for if anything? Do I just tell them to talk to the handyman? Obviously I can talk to him too. I just don't know who this falls back on for sure in the end.

If it needs a cleaning, do I appease them by offering to bring over my portable air compressor to try and clean it out?

This was a text message from late last night.