Gas Furnace Limit Switch Not Working

The flames would raise the temperature inside the unit and have no place to go getting hotter and hotter.

Gas furnace limit switch not working.

When your limit switch is not working correctly your furnace can overheat without shutting down as it should. Mount and fasten access panels correctly. The gas fired forced air furnace fan limit switch in the photo below is pointed to by the red arrow. If your gas furnace is blowing cold air a number of factors could be to blame many of which you can address on your own without the immediate help of a service professional.

Reset limit switch for stop start cycling. Also a malfunctioning switch may not send signals to the air handler successfully which may cause the handler to never turn on. Belts sticking worn or damaged. How to test and replace the fan limit switch on a furnace things to check before replacing the limit switch.

Furnace not working no gas flame. If the blower came on at the same time as the burner it would pump cold air through the house at first. The oil fired furnace fan limit switch shown in our photo below is in use on an oil fired warm air furnace where we can see about 3 4 of the silver colored dial where the fan limit switch settings are made red arrow. What happens if your furnace limit switch stops working properly.

Over time your furnace s limit switch can develop problems. Limit switch set wrong. If the temperature inside of the plenum gets too hot it shuts off the gas supply to your burners to prevent your furnace and heat exchanger from overheating. Replace worn or damaged belts.

A limit switch also acts as a safety device for your furnace. If it is set to off or auto the furnace s limit switch must be adjusted. Typically the lower pointer should be set to about 90. Limit control needs adjustment.

However for your own safety don t attempt to reset the switch without first consulting your furnace s instruction manual. Spray squeaking drive belts with belt dressing. It s possible to reset the switch at home when necessary by following a few simple steps. For example if the blower motor stopped running then no air would move through the unit.

The limit switch includes a sensor in the heat exchanger to. To troubleshoot a misbehaving gas furnace start with the easiest explanations and solutions then work your way to the most complicated. The function of your furnace limit switch is to tell the fan when to turn off and on depending on the temperature in the home.