Perform a visual inspection: Check your HVAC system regularly for warning signs that you need a professional to take a look. Catching problems early can save expensive repairs later on. Frozen coils, water leaks, and dirty evaporator or condenser coils could require an HVAC contractor's help. Watch the thermostat: Turning your thermostat even one or two degrees higher in the summer or a few degrees lower in the winter can save wear and tear on your system and make a big difference in energy usage.