If you have a valid written lease and can prove you paid the owner of record on the date he owned it you have a good claim to occupancy. The five day notice to vacate must be followed by a court order. If your leases expires in only 4 days I don't' see how the legal system could move that quickly. As far as the A/C repair goes I don't think you should expect any solution before you leave. This is one you may just have to chalk up to experience and add it to your war stories.
Best to try and work it out with the new owner-he doesn't want to pay the legal bill anymore than you do. If not you could call a real estate attorney and get some advice.
Best of luck.
Sounds like from what you said, you have four more days to go. I would try to work something out with the new owner. Show him the lease that you signed.
If you have other questions or need to find a new rental, just ask.
May I wish you the best.
Contact the Real Estate agent that you hired to help you.
Then hire an attorney.
Did you or your agent verify that the person renting the property to you was the owner or had the legal right to rent the property?
Is there a clause in your occupancy agreement regarding the sale of the property?