I am a certified heating and cooling technician, and my services are always in demand. Much of what I do is repair HVAC systems whose repair could have been avoided. It’s as easy as regularly changing the air filter, usually every two or three months. They should be changed more often if the homeowner regularly runs their air conditioner. I’ve come to realize that many people rarely change their HVAC filters more than once a year. Having said that, people often tell me otherwise. They lie right to my face that they change them every two months, when the evidence clearly says otherwise. Not only is the filter filthy, but the coils on the air conditioner are frozen. Nonetheless, it’s my job to educate the customer on the benefits of regular filter replacement. I also give them an information sheet on our company’s air filter replacement service. Every two months we send a filter right to their door, reminding them it’s time to make the switch. But I can tell by their response that they think I’m trying to sell them something that they don’t need. But just as they need to change the oil in their car, they also need to change the filter on their HVAC system.