Can someone sue me for a fire caused by faulty wires in an a/c after i service it?

Before i did any work on the unit i told him that i was not a license contractor. I check the unit and there where some burned wires in the inside unit which needed to be replace, he then said to replace the wires. A couple of months after i get a letter from the insurance company asking for money because i serviced it last although i did not give a receipt to my acquaintance cause he only gave me gas and new rewire money. I dont even know if i was the last one there.