Problems with furnace blower
I recently had an issue with a furnace blower that wouldn’t turn off.
The constant operation resulted in excessively high energy bills, and I worried about the heating system quitting entirely and not lasting as long due to wear and tear.
I hoped that by googling the problem and troubleshooting myself, I might avoid a costly repair bill from a professional. Online, several articles suggested that the thermostat settings might be the problem. The thermostat signals the furnace when to turn on or off. I first verified that the fan setting was set to AUTO rather than ON. In the ON position the blower is told to run non stop. In the AUTO setting, it only operates when the furnace is producing heat. I also checked that the temperature wasn’t set overly high, forcing the furnace to keep working in order to achieve it. Since I kept the thermostat set at around 70 degrees, I didn’t think this could be the issue. The next option was the fan limit switch, located under the furnace hood. I doubted that this hidden switch somehow got adjusted to MANUAL or ON but checked it anyway. I needed to remove the panel to locate the switch. I tried resetting it, hoping this would make a difference, but it didn’t. I had no choice but to contact an HVAC company and schedule a repair. Fortunately, I was able to get an appointment for the following day. The technician was scheduled to arrive anytime during an eight-hour window, which meant taking a day off from work. I was very pleased when I got a call in the morning with an approximate ETA and the technician showed up right on time. He discovered that it was a bad fan limit switch and had it fixed within an hour.