My furnace was shutting off by itself during the winter. Brendan at Ambient Air came to the house and did a furnace cleaning. He did VERY complete detective work to find the problem and ensure the safety of my family. He even let me in on a low cost solution to fix the problem long term. All I had to do was change from the washable filter to one that did not impeded the air flow as much. I will definitely use this company again and refer my friends.