Air conditioner problem. Please help!

最近一个房客三番五次来e-mail，一会儿说空调不work；我说去修，他又说好了。过一天又说空调又有问题，再一天又说没问题了。昨晚他又再次说空调有问题，我说我lg今天下午会他家查看，结果今天早上他又E-MAIL说：It's working for now anyway and I hate to have your hu*****and come down here for nothing. It seems to work better the lower the temp set. In other words if I leave it at 65degree, it will maintain. But if I set it at 72degree, it will wait until its 80 before it kicks on again. I still don't like having to run it that cold so I'd like someone to look at it soon.
我们现在白天室外温度大约80度，晚上才50度。我想家内温度怎么也不会超过80度。感觉空调挺奇怪的。大家觉得空调会有这样的问题吗？

这个房客一向按时交租，应该算是好房客。。。。