Residential HVAC sales can be a pushy business at times. Pushy because techs are trained to sell rather than service. Why is this? For profit I would imagine but we can generate nice margins by understanding the trade deeply and applying skill to seek out actual problems and recommending actual solutions. Check out Jobber www.getjobber.com/hvacknowitall Check out the article Gary McCreadie wrote on this subject. https://hvacknowitall.com/blog/the-truth-about-furnace-tune-ups Please follow me on my back up Facebook account. https://www.facebook.com/profile.php?id=61569643061429&mibextid=ZbWKwL