A side from some essential maintenance techniques, heating, ventilating, and air-conditioning systems are not fix-it territory, In fact, you should have them cleaned and serviced annually by qualified professionals not just to keep them in top working order, but as a safety measure as well. Good technicians will be able to tell you if you need to oil any motors regularly, what other routine maintenance tasks you need and how to do them, and when it's time to replace a system.