It never occurred to me that the thermostat in my home would take batteries; I just thought it wired directly into the house electrical wiring like the stove and light switches do. The thermostat is located on the wall, so that’s what I had figured. One Sunday when the A/C was not coming on, it never dawned on me that the thermostat batteries might have expired. I rose early one Sunday to go for a run before we went to church. The house was a bit warmer than normal inside, but I didn’t think too much about it until later. When I returned from running, it was extremely humid inside. I just thought that it was me being hot from my run. I showered real quick to cool down and stretched out for a short nap right after. About an hour later, I felt sick when I got up. It was extremely warm inside and I knew there was a problem with the air conditioning. The display on the thermostat was blank so I knew there must be a problem somewhere. I called the HVAC repair company that happened to be open Sundays and explained the issue to the woman on the phone. She inquired if I had ever put new batteries in the thermostat. She could tell by my confusion that I hadn’t. I looked all over the house for some AAA batteries for the thermostat, and after a few minutes I located a couple. She led me through the process of replacing the batteries and that fixed the issue right away. She was kind enough to save me an embarrassing and expensive service visit. I now know that the thermostat takes batteries, so I hopefully won’t have the same issue again.