(FWIW,$8K on just the compressor seem excessive.)Otherwise, unless your contract with your GC says they will provide 24/7 surveillance, or you can prove the AC was never installed, you own the problem.If the property has been vacant for more than 30 days, most policies won't cover vandalism unless you have added a Builders Risk Addendum.

I’m under contract for a small duplex in an opportunity zone.

Or should we sign the contract now and set the execution date for two weeks later?

The purchase contract makes the buyer legally responsible for the loan. 

If you do, tenants will contact you when your PMC tells them "no".With the deed and PMC contract, the new PMC should be able to convince most of your tenants to start working with them.

I own a property management company and also a contracting company in Ventura.   

I personally believe his contract job contract got cancelled as i know others from his company left that same week. 

I rent through Furnished Finder which has a standard rental contract. 

Water, power (no gas) are billed directly from the utilities company. 

So if all you’re looking for is to put a property under contract that won’t be hard.