Auto transformers by themselves do absolutely ZERO to protect against transient voltage spikes. If you are really worried about your refrigerator board, go to any supermarket and purchase a 300 watt COMPUTER voltage correction and spike clamping filter for around thirty dollars. CFE bases their electrical grid on 127 vac. The computer boxes are NOT for devices that have AC induction motors.
One of the WORST offenders is the roof air compressor starting and stopping. I've seen them induce a 300+ volt positive and negative oriented transient on my Tektronix scope for as long as 70 milliseconds.
