My furnace fan won't shut off automatically. It is possible for your furnace to run with blower motor off. 1. Furnace Does Not Blow Air. Also, the furnace is hot and the gas is burning. The furnace control board should start the blower motor within 1 minute after igniting the burners. Filter – The most common cause of furnace problems is a dirty filter. Step 1 Replace your "furnace limit switch." If you furnace filter is clogged, the airflow will be restricted. Electric Furnace Troubleshooting. Replacing it is an easy fix. Sending a bleach mixture or algaecide treatment down the drain may help prevent future clogs. Turn the power to the furnace off and disconnect the wires from the thermostat. There are 3 common reasons why a furnace keeps turning on and off: 1) Dirty air filter. If that does not stop the furnace blower, switch off the thermostat. Basic furnace operation and pilot lighting instructions are generally listed on a sticker attached to the front access panel. 1. Ensure That Your Requested Temperature is Reasonable. When I first turn on my furnace everything works fine. Trane gas furnace is not turning on automatically. If your furnace is coming on and isn't turning off, you need to investigate the issue, as it could end up costing you excess money on your utility bill at the end of the month. DIYJoe Member Posts: 4. After we changed the thermostat the furnace will not automatically kick on and it … I have to manually turn off the thermostat and on again to make furnace on. Thermostat not turning on heat Before you assume you have a furnace problem, do some furnace troubleshooting and check the thermostat to make sure it's actually telling the furnace to come on. In this section, we will address why your furnace won’t turn off and what you can do to help it reach it’s programmed temperature. The part they are probably leaving out is that on the thermostat they are switching the fan to "ON" in order to get it work.. which means the fan does not turn off once the furnace shuts down. The Furnace Won’t Stay On If the furnace fires up but then shuts off after a few minutes, it could be that the control board is faulty. A dirty air filter restricts air from getting into your furnace. Check to make sure the gas control valve to the furnace is open. That’s no good. However, the fan will work when the thermostat is set to the ON position. I replaced the thermostat and get the same results. I think what the OP is suggesting is that if the fan is set to auto and furnace comes on, no heat (or at least, very little heat). Or, if you smell gas, leave immediately and call a repair company. First, turn off all power to the unit and turn off the gas at the gas valve that serves the furnace. The furnace’s control board thinks that the furnace is overheating so it runs the blower. If you find that your furnace is not igniting at a time when you need it most, try these easy fixes first in an attempt to get your heating system up and running in a short amount of time as possible.. If these tips don’t work then give us a call or find us on Facebook. it's likely the furnace. Thermostats, especially programmable ones, can be complicated, and the more options a thermostat has, the more that can go wrong. Note: If you or a tech has recently tampered with your furnace, it’s possible that the fan limit switch was set incorrectly by accident. Your furnace’s heat exchanger needs that air blowing over it or it overheats, causing the furnace … It's a gas forced air furnace. Verify the unit has power. In case the furnace turns off when the thermostat is turned to off, a probable reason is a thermostat that is not working properly. This switch usually powers the low-voltage thermostat as well as the furnace itself. If the flame sensor does not detect a flame, as a safety precaution, the control board will shut off power to the gas valve to prevent the furnace from heating. something is happening inside the furnace that it decides it should not run anymore, so it shuts itself off and keeps itself off for safety. Believe it or not, a dirty air filter can actually make your furnace run non-stop because it restricts air coming into your furnace. I go down and turn the power switch on the furnace off and on a couple of times and then you can hear the igniter and the furnace fires right up and will continue to run just fine. Those primitive models relied on a bi-metal spring to sense temperature. If it is not open then your furnace could have no fuel. Bad Belt. pretty sure that is how they are getting around the issue. If the drain is clogged, insert a straightened wire hanger to clear it out. Review the furnace instructions. It is an older furnace, and I have checked the thermostat settings. A furnace that frequently shuts off automatically may have other issues, such as a clogged air filter or blocked ducts that are causing the furnace to overheat. My furnace fan/blower will not work when set to the auto position. Improper usage or maintenance of your furnace could result in the furnace not functioning, fires, explosions, property damage, personal injury, or … Manufacturers would affix a mercury switch to the outside end of that coiled spring. When the mechanical thermometer is switched to "AUTO", I could hear the click sound from the unit, however the FAN does not start blowing the hot air at all. When the system is working, the thermostat does keep the house properly conditioned. RSP Heating and Cooling is the best company to go to for furnace repair and maintenance. When I do turn the fan to the ON position, no hot air is blowing out of the vent. The blower motor is what blows air over the heat exchanger. To turn the furnace back on, relight the pilot light.If it will not stay lit, however, turn off the furnace’s power and gas supply and try the following. The furnace is a Concord 90% Efficient, gas fired, forced hot air unit with a White-Rodgers mercury switch thermostat, 5 years old. Clattering sounds: Check the access panels on the furnace itself.They can work loose and rattle, with the annoying sound carried through the house on warm air from the furnace. The lockout condition can be reset by turning the thermostat off and reducing the temperature to a value which would not cause the furnace to turn on. If your furnace’s motor runs but the blower doesn’t move air, the belt that connects the two probably has broken. About 4-5 times now when it called for the furnace to warm up the house to 68 f the furnace has not come on. If the furnace starts, the problem is either with the thermostat wire or thermostat. Once the rising liquid hits a sensor, the furnace will automatically shut off to prevent the condensate from spilling over the edge. Also, if the fan limit switch override (a small knob on the switch) somehow got set to MANUAL instead of AUTO, the blower will run constantly—whether or not your furnace is going through a heating cycle. Cause #4 Furnace Blower Motor Not Working. This is most common cause of short cycling. Many homeowners discover that their furnace is not working when they go to turn it on for the first time of the winter season.. but you didn't tell us anything about the furnace, so we can't provide any more detail. If the blower starts by turning the thermostat fan switch to the "On" position, but does not come on automatically after the burners have ignited, this may indicate a faulty control board. Other causes of furnace turning off and on. Just cool air blows. Show More. This is the part of your Furance that heats the air. The solution to … Moving the temp control makes no difference, ONLY toggling the on/off switch on the thermostat will kick on the furnace. 2. If you have an older furnace with a pilot light, it is possible the flame might have gone out. The thermostat still turns the heat on and off but the fan doesn't go off when the heat goes off. The thermostat seems to be working but the thermostat is not turning on the furnace… Check the condensate pan for this problem. Try replacing its batteries if the display on a traditional low-voltage thermostat or wifi thermostat is not indicating power. Furnace Blower Fan Wont Turn Off - Hello Richard, I have a problem with my furnace where the indoor blower will turn off.My furnace seems to be heating okay it is just the blower will not shut off. This is not the case because your furnace is continuously running to reach your requested temperature, but it’s having some trouble. Changed Thermostat will not automatically turn Furnace on [ 1 Answers ] We changed our old honeywell thermostat (with mercury) to an updated honeywell thermostat (with no mercury) CT87K. Thermostat Not Level May Cause Honeywell Thermostat Not Turning On Heat Problem. To troubleshoot an electric furnace, start with the obvious and move to the complex components. I toggle my dometic digital thermostat to furnace, I hear the relay in the overhead fan click, the blower start, and within 5-10 seconds the igniters ignite and hot air is blowing out of the ducts. December 2019 in Gas Heating. According to the professional, it seems to be caused by the defective heat sensor/thermostat on the furnace … The furnace switch is usually mounted on a wall near the furnace, or sometimes even on the furnace itself. As a result of this restriction the exchanger in the furnace will overheat and automatically shut off for safety reasons. Initially, the burner will turn off and then the blower would turn off as well. Replace the wire or thermostat to fix the problem. A furnace could potentially not turn off for a few different reasons. The furnace blows hot air only in "FAN" mode. I would suggest that you check your limit and rollouts to make sure they are all closed with a voltmeter. Wait approximately 30 seconds and then turn the thermostat back on and increase the temperature to the desired level. However, when the fan switch is switched to AUTO position, and the room temperature is below the setting temperature, the furnace is on, but the fan/blower is not. I set my thermostat 70 degree and furnace will work and make my home 70 and turn off but once temperature drops it won’t on again the. Furnace fan/blower does not turn on automatically The furnace fan/blower can be turn on manually (switching to ON position from the thermostat--Maple Chase 9600). Step 6: Clean the Pilot. 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