Each state has its own Landlord Tenant Act. Check out AZ here....
http://www.tenant.net/Other_Areas/Arizona/AZresidential.html
Under Az law the landlord is REQUIRED to
"Maintain in good and safe working order and condition all electrical, plumbing, sanitary, heating, ventilating, air-conditioning and other facilities and appliances, including elevators, supplied or required to be supplied by him."
and
"Supply running water and reasonable amounts of hot water at all times, reasonable heat and reasonable air-conditioning or cooling where such units are installed and offered, when required by seasonal weather conditions, except where the building that includes the dwelling unit is not required by law to be equipped for that purpose or the dwelling unit is so constructed that heat, air-conditioning, cooling or hot water is generated by an installation within the exclusive control of the tenant and supplied by a direct public utility connection."
If the landlord does not comply
"§ 33-1364.Wrongful failure to supply heat, air conditioning, cooling, water, hot water or essential services
A. If contrary to the rental agreement or § 33-1324 the landlord deliberately or negligently fails to supply running water, gas or electrical service, or both if applicable, and reasonable amounts of hot water or heat, air-conditioning or cooling, where such units are installed and offered, or essential services, the tenant may give reasonable notice to the landlord specifying the breach and may do one of the following:
1. Procure reasonable amounts of hot water, running water, heat and essential services during the period of the landlord's noncompliance and deduct their actual reasonable cost from the rent. If the landlord has failed to provide any of the utility services specified in this section due to nonpayment of the landlord's utility bill for the premises, and if there is no separate utility meter for each tenant in the premises such that the tenant could avoid a utility shut-off by arranging to have services transferred to the tenant's name, the tenant may either individually or collectively with other tenants arrange with the utility company to pay the utility bill after written notice to the landlord of the tenant's intent to do so. With the utility company's approval the tenant or tenants may pay the landlord's delinquent utility bill and deduct from any rent owed to the landlord the actual cost of the payment the tenant made to restore utility services. The tenant or tenants may continue to make such payments to the utility company until the landlord has provided adequate assurances to the tenant that the above utility services will be maintained.
2. Recover damages based upon the diminution in the fair rental value of the dwelling unit.
3. Procure reasonable substitute housing during the period of the landlord's noncompliance, in which case the tenant is excused from paying rent for the period of the landlord's noncompliance. In the event the periodic cost of such substitute housing exceeds the amount of the periodic rent, upon delivery by tenant of proof of payment for such substitute housing, tenant may recover from landlord such excess costs up to an amount not to exceed twenty-five per cent of the periodic rent which has been excused pursuant to this paragraph"
Read the whole act for more info
