Most units stop working temporarily or completely go out do to not keeping up with the quarterly maintenance of the unit.
A few easy steps to help this without getting into the technical stuff is to go outside where your unit or units are located and check for the cleanliness of the unit. Follow these steps:
1.) Take off all panels that cover the coils.
2.) Get a soft brush, water, and non acid coil cleaner ready.
3.) Use a small portion of water with your brush on your coils. IMPORTANT: DO NOT BEND COILS
4.) Do the same with the non acid coil cleaner.
5.) Reinstall panels back to your unit or units.
Doing this will allow your unit to breath keeping it from freezing and working hard to provide you heating and cooling.
This is one of many of the quarterly maintenance needed for your unit to live the longest!
If you do not want to deal with this yourself we have quarterly maintenance plans that you can get on to guarantee your unit lives the longest life possible.