AC cannot cool below 78F

[James Kandasamy]

Hi BPers,

We have a house that was built in 1984 in Texas. The tenant claims that the AC cannot cool down below 78 F. The outside temperature was around 100 F when they claim this. The AC is running all the time. The AC man says that its common for this type of house and it only cools down to 78% of outside temperature.  The tenant claims that because the AC cannot cool below 78 F, its a safety issue for the tenant. The tenant age is in their 70s.How do i handle the tenant's complain ?

James and Shanti