For those who believe that a yearly HVAC check-up and service is not needed are foolish. Why? Because the tech can find components such as the capacitor going out of spec which will put more strain on the compressor and shorten the life of your system. Also, cleanig the coils, inside and out, will make the system run more efficiently saving you money over time. They also measure the current the inside and outside fan motors are drawing, and test to make sure your Auxillary heat coils, which most have, are working properly. Also testing the coolant will let you know if you have a leak. Typically, you A/C should never need coolant unless there is a leak somewhere. Again, running your A/C with low coolant eventhough it's still cooling in your opinion will shorten the life of your system. There is no way to know unless you test the various items. Your HVAC system is not an item you should forget and don't do any maintenance untill it fails. In the long run you will be spending more money.
All this said, you need to find a company such as Sunshine, Munns, and other larger companies that don't need to resort to these scams to stay in business. And if you are one of those who are able to change the capacitor yourself, all you need to do is when the tech says it needs replacement, tell them you will do it next time around and do it yourself after he or she leaves. Just remember get the
US brand capacitor such as this brand from Amazon which is what your HVAC company uses and not the cheap Chinese knock-offs. Make sure you check the rating you need for your machine. The cheap Chinese capacitors are less reliable and wear out faster especially in our hot Florida weather so in the long run it's not worth the savings. You get what you pay for.
Amazon.com