1) If the A/C remains out and the lack thereof is rendering the premises not merely unpleasant but essentially uninhabitable--not fit to live in--then that might constitute grounds to terminate the lease for a breach of the "implied warranty of habitability." However, if either the A/C has been fixed or the premises are liveable, you cannot terminate the lease, though you might be entitled to some monetary compensation for the time you lived without A/C.2) The landlord's or manager's continued violation of your right to possession by entering without proper notice and for proper reasons (e.g. 24 hours notice for inspections, maintenance, or to show for sale or rental), consent, or for an emergency (e.g. gas leak) could provide grounds to terminate the lease, but it may be very difficult to prove that they did this based solely on the A/C being on full blast.3) Paying for gas when the lease says you should not would not provide grounds to terminate the lease, though you could sue to recover the money you paid but should not have.4) A building or apartments being sold does not provide grounds to terminate a lease. The new owner takes the property subject to the lease and becomes your new landlord.