High Limit Switch Furnace Troubleshooting

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

High limit switch furnace troubleshooting. Clogged furnace filter a dirty or clogged filter blocks the air flow into the furnace which may raise the inside temperature of the unit. How to check limit switches using your voltmeter. When the temperature gets too high the high limit switch turns off the gas to the furnace. This article describes in detail the testing and diagnosis of problems with warm air heating furnace combination controls also commonly called the fan limit switch on warm air heating systems.

The high temperature limit switch senses the temperature of a furnace and tells the blower fan to turn on and off at the appropriate times. Flip the switch on the side of your furnace and flip the breaker off and on again before you even think about replacing any parts. Fan control limit switch. As a safety the high limit switch turns the gas off when the temperature becomes too high.

It also can shut down the furnace burners it if gets too hot inside the furnace. If the furnace failure code indicates an open limit or open high temperature switch or open rollout switch it is probable that the furnace has overheated. For example if the blower motor stopped running then no air would move through the unit. As a working example we examine the honeywell combination fan and limit control type l4064b.

Next check the filter. High limit switch a high limit control switch will turn off the gas to a furnace if the temperature becomes too high. Limit switches turn off the burner and turn on the circulating fan if there is a high temperature condition in the furnace. In this episode of repair and replace vance shows how to replace the high limit switch in a gas furnace.

The limit switch is a safety switch that monitors t.