It s function is to monitor the combustion chamber heat level.
Atwood furnace limit switch test.
If there is a serviceman switch turn it off.
The fan limit switch temperature settings shown on the dial sketch are discussed separately.
The limit switch is a simple temperature controlled switch.
If the temperature of the combustion chamber exceeds the preset limit the switch will open and disrupt the flow of current to the circuit board in effect shutting down the main burner.
A limit switch is a device that s located under your furnace s supply plenum.
If the gas solenoid is opening up but it is not sparking then the electrode would be suspect as the board sends a signal to the gas solenoid and electrode at the same time.
Depending on your furnace model the switch will be surrounded by a silver or white cover.
It reads the temperature of the plenum and waits until it gets appropriately warm.
If not shut the power off at the breaker panel.
It will be located at the top of the panel.
The furnace will not spark unless you have continuity through the sail and limit switch if you have continuity then the circuit board is suspect and can be tested with a special board tester.
At fan limit control settings.
If the temperature inside of the plenum gets too hot it shuts off the gas supply to your burners to prevent your.
Before testing the limit switch power off the furnace wait a few seconds and power it back on.
Some furnaces will try a set number of times to start usually three if it fails then it will have to be reset with a power off before it works again.
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.
Assure that the control has been installed and wired in accordance with the manufacturer s installation instructions using the following procedures.
To test a limit switch you ll want to check continuity to determine what state the switch is in.
How to check the furnace fan limit control switch wiring.
Ordered new limit switch atwood 37022 hydro flame limit switch 190 degrees around 15 with shipping paying attention to get one with correct limit temperature and also trying to find out with rv manufacturer for no reason i decided to contact them not atwood whether it s possible to take sail switch out without taking the furnace unit out.
A limit switch also acts as a safety device for your furnace.
Open the access panel and locate the high limit switch.
