I was getting no heat and the technicians found that I had a damaged circuit board. It had to be ordered and they were to return about a week later. (Unfortunately, they tried to call me a few days early to install the new circuit board but I was otherwise occupied). The technician called to let me know he was on his way and installed the circuit board quickly and I could hear the sound of the heater starting up! He vacuumed the area and was done within the hour.