Setting Fan Limit Switch Gas Furnace

Locate your fan limit switch your fan limit switch is located inside the furnace panel cover usually near the upper right corner.

Setting fan limit switch gas furnace.

When the air in the plenum reaches the high limit setting on the limit switch the switch turns on and activates the blower fan circulating air through the heat exchanger on its way to the house while simultaneously pulling cool air from the house through the air returns and into the furnace. The limit off indicator setting red arrow in our fan limit switch photo at above left is a safety control that will turn off the oil or gas burner if temperatures inside the warm air plenum exceed a safe level. The furnace s lower limit switch is programmed for automatic reset but the upper limit switch must be manually reset. It works off of temperature and also provides a high temperature safety limit this is a switch actually two switches which turns the furnace blower on and off based on the temperature of the heat exchanger.

Step 1 open the cover of your circuit breaker box. In many models it also has a built in safety control for the burner to shut off at higher temperatures if the burner s inner control malfunctions. Honeywell furnace temperature fan limit switch control the fan limit control turns the fan on and off in furnace applications. The fan limit control switch on a furnace regulates when the blower will come on or shut off.

A fan limit switch is a component of a furnace system that determines when the furnace blower assembly for hot air turns on and off. 200 f by keeping the fan off until the supply air plenum is warm the heating furnace limit switch prevents the furnace blower from sending chilly air into the building if the oil or gas burner has not sufficiently heated up the furnace heat exchanger and supply air plenum. This is used so that cold air is not blown into a house waiting for the gas flames to heat up enough before the blower turns on. Setting the fan limit control switch properly will prevent damage to the furnace.

This is the highest temperature setting on a furnace combination control. Fan control limit switch the fan switch reads the temperature inside a furnace and once the temperature becomes warm enough turns the blower motor on sending warm air into a home.