Furnace High Limit Switch Open

Locate the white limit switch.

Furnace high limit switch open. They will be mounted near where the flame may rollout the front of the furnace due to venting blockages heat. The high temperature limit switch is an important device used in forced air furnaces powered by gas or heating oil. It will be located at the top of the panel. I have the the amana air command 80 high eff gas furnace and the unit works for 3 4 hrs cycling on and off normally then will shut down and won t start again until the unit is powered off reset.

So to put it simply the limit switch tells the furnace fan when to turn on and when to shut off and it tells the furnace to shut down if it is overheating. Some of these parts are shown on the left. Attempting to reset the furnace limit switch while the power is connected may result in electrical shock. It s also known as a fan limit switch or simply a limit switch.

The switch makes sure the furnace is operating safely and at its desired settings. It reads the temperature of the plenum and waits until it gets appropriately warm. The vent limit switch which is also referred to as a fan limit switch and is typically shaped like a small metal disc prevents damage to your furnace by shutting the furnace down in the event. Founded in 1982 goodman manufacturing is an american company that produces heating and air conditioning equipment for residential and commercial customers.

The limit switch will open periodically to prevent over heating. Remove the cover by lifting it upwards or pulling it off to reveal the body of the switch and two metal arms. A fault will appear when it s open or if it doesn t reset within a specified period of time during which the blower is expected to circulate enough air to cool the heat exchanger to. Depending on your furnace model the switch will be surrounded by a silver or white cover.

I have a 1994 lennox 80 mgf series furnace and there is a 4 ligh flashing which say high limit or rollout switch open. Once the plenum reaches a specific temperature the limit switch sends a signal to the air handler to begin running and delivering warm air to your home. A limit switch is a device that s located under your furnace s supply plenum.