One major factor that voids many warranties is lack of maintenance. For instance, having your air conditioner (or furnace) maintained annually. If you don’t have documentation that your system has been maintained according to the manufacturer’s requirements, they may not cover any necessary repairs. Next, never order any parts from the internet. Only order parts and have them installed through a licensed dealer. Saving a few dollars on a part voids the entire warranty. Third, a proof of purchase may be required if your system needs any maintenance done under the warranty; keep it near the owner’s manual and warranty information so you can’t misplace it. Keep in mind, new systems must be installed by a licensed HVAC contractor. Any system or component not installed by licensed contractor will void the warranty for the entire system. It’s worth it to work with reputable companies when the investment numbers in the thousands of dollars. Last, if any heating and cooling equipment is moved from its original location in your home, the warranty will be voided. Never alter your system or use it for unintended purposes.