There are many types and costs of AC voltage regulators which can be used. I would look into using a UPS in which the AC voltage is always being generated internal of the UPS, ie, the line voltage is converted to DC, which has a DC to AC inveter producing the AC. If you lose line voltage, the DC from the battery produces the DC for ihe inverter. It is seemless and instantaneous. A 500VA unit will be sufficient for several electronic items.
If this is above the cost range, a buck/boost isolation trnsformer can be installed. This will filter out voltaage spikes(very rapid transients), and has a special winding to either add to or subtract from the output voltage to maintain it to 120vac.
I would first ask the elec. company to connect a voltage max./min. monitor so that the voltage fluctuations can be recorded. Sounds like their problem, but getting them to address it, may be tricky. Has anyone else on the immediate vacinity had problems?
The compressor running backwaards sounds strange. Give the model #, assume a gast? I will look up the type motor and comment.
