Winter electricity tension when the air conditioner encounters voltage instability how to do?

In the winter peak of electricity consumption, the situation of voltage instability may appear in certain circumstances, at this time, it depends on whether the home appliances can withstand. If the voltage is unstable in use, the appliance can not withstand this voltage change, it is likely to short-circuit or fault. Take air conditioning as an example, if you encounter voltage instability, what should you do?