My sister called me up the other day to see if I would come and help her fix her air conditioning system. I don’t know about your sister, but I never hear a word from mine unless she’s wanting me to come and fix something for her! Sometimes it gets to be annoying, but I try to be a good brother so usually I go over and help her if I can. Anyway, we were still having really hot weather and high temperatures here until just the last week or so. Up until then, the weather had been unseasonably warm and everyone was still using their central air conditioning systems in their homes, including me and my sister. Well, on one of those really hot days, my sister’s A/C system just up and stopped working altogether. She told me that she wasn’t really sure what in the world had happened, and she also didn’t know how to fix it. She was really sounding stressed out about it because my sister is just not someone who can live for very long without air conditioning whenever it’s hot outside. I told her that I would come over and look at the A/C unit for her. Even though I’m not a professional HVAC technician or anything, it sure didn’t take me long to figure out what the problem was. My sister has three big, hairy dogs that she loves more than life itself. She hadn’t changed her air filter in a while and the whole thing was completely clogged up with tufts of dog hair!