During the hottest weekend of the spring, our ac system just stopped, about 9 pm. Literally sweated it out, till 830, called and was scheduled for service call. Dispatchers were patient, and empathetic.
I was assured that the tech would show up. At 1900 Tim And Tony showed up, I described the symptoms. 10 mins later we have cool air again. They showed me the old part, where it came from, answered questions and were very friendly.
Sierra is on my permanent TO CALL LIST. For heating and air!