Bill Nyquist needed a little extra heat and air conditioning for a guest room above the garage at his Mendham home. He purchased an LG mini-split heating and cooling unit seven years ago but it doesn’t get a lot of use —- maybe twice a year, he said. When it’s on, it does the trick. It stopped working in September 2021, so he called an authorized LG repairman. “The technician found most of the electrical components were faulty,” Nyquist said. “He called in-house technical support and found that the street voltage was higher than what the unit can support.” The technician suggested Nyquist call…