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Understanding Your Furnace’s Limit Control Switch

The limit control switch is an important part of your furnace’s blower system, whose job it is to distribute warm air throughout your home. Yet few homeowners understand the precise role played by the limit control switch. if you would like to improve your knowledge of furnace components, read on. Here you will learn about the job of the control switch, as well as common problems it faces.

Blower Operation

Understood at its most simple, the limit control switch turns the blower fan off and on. It knows when to do this thanks to a special built-in thermostat. This thermostat is responsible for monitoring the temperature inside of the furnace. When it detects heat being given off from combustion, it sends a signal to the limit control switch, which in turns starts up the blower fan.

Safety Switch

The limit control switch also has another important duty: acting as a shutoff switch for a furnace that has grown too hot. If the thermostat registers a temperature above the safety threshold, it automatically cuts off power to the furnace. This helps to reduce the risk of explosions, fires, and other disasters associated with an overheated gas furnace.

Limit Control Switch Problems

Of course, the limit control switch is subject to certain problems of its own. The most common problem involves no longer being able to accurately gauge temperatures. This usually happens as a result of a thermostat that has become damaged or improperly calibrated. It may then register an excessive temperature even when the actual temperature falls within safety thresholds. This annoying problem leads to the furnace shutting down before it has finished heating your home.

If you have been struggling with a similar problem, feel free to contact the pros at ABA Heating and Cooling. They will be able to assess whether a bad limit control switch is at the heart of the issue.