https://www.harsterheating.com/services/ – Harster Heating & Air Conditioning’s first concern is you and your family’s safety. We follow through with that by offering FREE heat exchanger inspections. If you want to make sure your heat exchanger is in good shape – even if you’re not quite sure what a heat exchanger is or what it does – you at least know who to call. Learn how to avoid a potentially unnecessary service call by following these steps to troubleshoot a furnace that won’t turn on.