Is landlord required to fix broken air conditioner?

1:Ted Kimball emailed April 2013 "Habitability is interpreted differently by various judges. Habitability legislation is not the entire law, it started with case law and continues to be interpreted in various degrees. Lack of A/Could be a habitability issue especially if the property is East County where it gets very hot in the summer and fall. On the other hand, an A/C unit that fails in the winter would most likely not be. You cannot by disclaimer or otherwise, identify what is and what is not habitability. The tenant cannot waive or reduce their rights in this area of law."

2: If a 30-day notice of change of tenancy is given that the landlord will no longer fix the AC , there is a risk this might be used by tenant in a defence in an eviction action for non-payment or rent 

3: If the A/C does not cool the entire residence then this should be disclosed to prospective renters (as it is a latent        defect (as per Ted K email to JB on Feb 11th 2018)