AC Doc installed our current gas furnace and central air conditioning and have kept them running efficiently ever since through their annual preventive maintenance contract. AC DOC serves most of Northern Virginia including Sterling, Leesburg, Reston, Brambleton, and Herndon. We pride ourselves on providing superior value and individual personalized HVAC service that only a smaller company can. So whether your furnace needs repair or your air conditioner needs to be replaced, our licensed and well trained service technicians respond quickly to provide estimates and solve all of your heating and cooling problems.