I do ac for a living. About the best thing you can do and the cheapest is insulate your roof. If you can stop the heat soak you can probably manage it. I would say use a spot cooler and just have it blow in your direction. If your only staying 3 years ,I can't see dropping 15k for ac
Change the battery's in your stat and clean the coils. I had a problem like this for a customer, he had a short on the stat wire. It was shorted on the suction line. When it was dri it would be fine. After running for a wile it would condensate and short it out
When we're born we have no stuff, when were kids we ask people to give us stuff. When we're older we get a job to buy our own stuff. When we get evin older we collect stuff. When we die our wife sells all our stuff. What's the point of getting stuff anyway?