Rent and Utilities: Knowing the A.c. Unit Wasn't Sufficent but Didn't Replace It

My question involves landlord-tenant law in the State of: Louisiana I moved into a home and I love the home, but the electricity bill was and is very costly. Got the energy company to come out and check the meter and they said nothing was wrong with it, I noticed that the master bathroom's toilet water was attached to the toilet instead of the cold, they changed it out, but utility bill was still high. A contractor came out and looked at the a.c. unit, he advised me he told my landlord that this unit was outdated and advised him to get another one. He ignored the advice and now 2years later he's replacing it because I stated im on the verge of moving to a more energy efficient place. The unit presently is a 2ton and the replacement is a 5ton, that's the proper fit for the size house. Are they liable for the cost of the high utility bill I only asked that they help with the last 2 bills and he declined. My landlord also told me he know the unit isn't great he has gotten his use out of it and replacing it ,but what about the 2yrs of him knowing the extra financial strain he was putting on me and he done nothing about it

Rent and Utilities: Knowing the A.c. Unit Wasn't Sufficent but Didn't Replace It