We recently purchased a bi-level house which has a flat roof with no visible ventilation. We do not have a working a/c unit for 2nd level of the house and it's like a sauna day and night. We have ceiling fans on the 2nd level but all they do is push the hot air around. We get no relief from these 100 degree temps. Any suggestions besides the obvious of getting our 2nd floor a/c unit working?