Why does my furnace blower turn on then off?

Often when a blower turns on and then off again then on again at the end of a furnace burner-on cycle it suggests that the residual heat in the heat exchanger is heating up air in the plenum enough to turn the blower fan back on again.

What causes Furnace Fan to cycle after call for heat?

After it heat and gas shuts off fan will recycle a few times. New Thermostat, Clean filter, blower motor and housing. Tested the two limit switches one in heat exchanger about 3 in long one by downdraft reset type with button Both are O.K. Bypassed limit switches and it does same thing? What Else could be causing this?

What to do if your furnace is not producing heat?

Most furnaces also have a reset button that clears any issues that might cause the furnace to produce no heat. Check the thermostat and ensure it is set properly. Set the thermostat to “heat” and set the fan to “auto.” Adjust the thermostat approximately 3 to 5 degrees above the room’s current temperature to check if the heat comes on.

When to turn on the heat exchanger blower?

Tells the blower when to turn on (by measuring the temperature of the heat exchanger) Turn the blower motor ON (when the heat exchanger rises to a certain temperature at the start of a heating cycle) Turn the blower motor OFF (when the heat exchanger drops in temperature after a heating cycle)

Why does my furnace turn on but no heat comes out?

Dirty filters are the most common cause of furnace problems. Dust and dirt restrict airflow—and if the filter gets too clogged, the heat exchanger will overheat and shut off too quickly, and your house won’t warm up. If the blower is running but no heat is coming out, replace the filter.

Why is my furnace blower not working?

One of the most common problems with furnace fans is a bad blower relay . The first thing to do is check the relay or voltage from the board. If no voltage is recorded, you will have to replace the board or the relay. If there is a battery, check if it is working properly. This is another common reason behind faulty blower fans.

Why is your furnace blowing cold air?

Your furnace may be blowing cold air because the filter is too dirty. A dirty air filter blocks airflow over the furnace’s heat exchanger, causing it to overheat. When overheating, your furnace can trip a high limit switch, causing the furnace burners to shut off so that the heat exchanger does not crack.

Why does my Furnace Fan keep running?

Why Does My Furnace Fan Keep Running? Your furnace fan limit switch is set to “manual override” The fan limit switch is faulty and needs to be replaced There’s a problem in your thermostat wiring. Unfortunately, you’ll need a professional to fix those last 2 problems.