is there a law that requiers the landlord to connect the swamp cooler when temps are mid 90s to 100 and over.

A landlord must keep the property in a habitable condition.  Landlord must make sure that residential rental properties do not violate provisions of housing or health codes concerning the health, safety, sanitation or fitness for habitation of the dwelling unit.  Landlords must make sure that the unit has (1)  waterproofing and weather protection of the roof and exterior walls, including windows and doors; (2) adequate plumbing facilities; (3) water supply which is under the control of the tenant or landlord capable of producing hot and cold running water and sewage disposal; (4) adequate heating, ventilating, air-conditioning and other facilities and appliances, including elevators, maintained in good repair; (5) adequate electrical lighting, outlets and wiring; (6) adequate trash receptacles; (7) maintenance of common areas, floors, walls, stairways and ceilings.  If you Landlord contracted to provide ventilation and air conditioning, the refusal to provide the same constitutes a breach of the covenant of habitability, and there are remedies available to you once you have notified the Landlord and given the Landlord the opportunity to cure.