You're arguing a different point. The refund is because the beach of contract was only for a specified time. A total refund provides no incentive to attempt to rectify the situation.
Does that matter? Because there was no work around anyway. Sure they tried to find an AC tech, but ... haven't, so no AC in 80 F (26.6C).
A partial refund would incentivise we-tried-our-best problem solving.