We have an "AllStyle" brand mini-split AC in our bedroom. It's about 1.5 years old. It works fine, except about a month ago, it started "popping" and "cracking"--making it virtually impossible to get a good night's sleep! The sound is like that of plastic-on-plastic expanding or contracting (because of the temperature change), but it's never done this before. We called an AC repair guy, but he said he couldn't do anything about it, except replace the whole unit. Of course, they charged us for the trip anyway.

The units cools fine--but the popping noise is driving us crazy! Any advice?

This is one you will have to open up and dig into because the problem cannot easily be found. Noises are hard to locate sometimes but if you look long enough inside the unit you will find the problem.