sold a 5 ton new- out the box- air conditioning unit on craigslist.

Interested party called in obtaining the unit. She asked if it worked. I replied, to my knowledge yes. We never ran it because we didn't need it. Buyer decided to purchase the unit, but I did encourage her to have a technician with her to further examine it. Nevertheless, buyer paid $500 for it and had it loaded on a van and parted. 3 weeks passed and she called stating unit doesn't work. Buyer demanded a full refund. Is she entitled? Anything could've occurred in that time.