Last night we came home from work at 8 PM and our AC was not working and our Nest thermostat was saying there was no power to the thermostat. The circuit was not tripped, so I knew we had a serious problem. I called American Cooling and Heating, and they answered the phone right away. Tim arrived at our house within an hour, and discovered that our air handler disconnect switch was bad. This is literally just a standard light switch that turns the unit off, and he doesn't have one on his truck because it's not something an air conditioning company usually deals with. In fact, he said he has never seen this switch fail in all his years of work! Fortunately this is a $2 part that I can install myself, so I went to buy a light switch to replace the faulty one. I bought it, I installed it, and the AC came back on right away. Thanks for the excellent troubleshooting Tim!