Is air conditioning units considered part of a building or personal property?

The best thing for you to do at this point, and with the limited information  you provided here, would be to make sure you have a full copy of your insurance policy.  If you do not have a full copy or are unsure, you should request a copy from the insurance company.  Be sure to request a full copy with all declarations, exclusions, etc. and request a certified copy, if possible.  Once you have the full policy, read the entire thing -- all pages!  See if there are any exclusions relating to AC units or that would seem to fit this incident.  It all depends on what the insurance policy says.  You could also ask the insurance company to provide you with a copy of the exact exclusion that they are relying on. They should easily provide this information to you and if they don't, you may want to seek legal assistance. If there is a specific exclusion for this incident, then you probably won't be able to do anything.  Best thing to do for now is get and read the policy because it all depends on what it says.  Best of luck. NOTE:  This response is general in nature and should not be considered legal advice.  No attorney-client relationship exists or has been formed by this information.