Caring for a large heating and cooling system

I’ve a good friend, Hannah, who is a really sweet person but a total idiot. I really don’t know how she managed to graduate high school and make it through college. I don’t know how she manages to find her way to  and from home to her employment everyday. She does the dumbest things and sometimes calls me for help. One time, she complained  that her air conditioner wasn’t working and she needed the phone number of my HVAC contractor to repair it. I gave her the number of my HVAC specialist and recommended that she sign up for a maintenance plan. I later found out that she was talking about the air conditioner in her car. She had scheduled a visit with the HVAC contractor, and was frustrated when the technician refused to work on her vehicle. When her furnace wasn’t working right, I figured I better give it a quick look before she phoned a HVAC contractor. I asked her when she last changed the filter, and she said that she changed it  every morning. I then realized that she changes the filter in her espresso maker every morning but had virtually no clue her furnace even had a filter. I showed Hannah where to find the filter in her HVAC system and tips on how to change it. I told her to  replace it every month through the winter. When the furnace still wouldn’t start up, I checked the batteries in her thermostat. Although replacing the batteries fixed the problem, I still insisted that Hannah contact my HVAC company to arrange a regular service plan. Since she has no idea how to take care of her furnace and air conditioner, she definitely will need to have a  professional clean and inspect the equipment every six months.

HVAC unit