Atwood Furnace Limit Switch Test
A limit switch is a device that s located under your furnace s supply plenum.
Atwood furnace limit switch test. Depending on your furnace model the switch will be surrounded by a silver or white cover. The limit switch is a simple temperature controlled switch. Remove the cover by lifting it upwards or pulling it off to reveal the body of the switch and two metal arms. 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.
If there is a serviceman switch turn it off. It s function is to monitor the combustion chamber heat level. A limit switch also acts as a safety device for your furnace. It will be located at the top of the panel.
How to check the furnace fan limit control switch wiring. At fan limit control settings. The fan limit switch temperature settings shown on the dial sketch are discussed separately. To test a limit switch you ll want to check continuity to determine what state the switch is in.
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. 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. Assure that the control has been installed and wired in accordance with the manufacturer s installation instructions using the following procedures. 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.
It reads the temperature of the plenum and waits until it gets appropriately warm. Locate the white limit switch. If not shut the power off at the breaker 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.
How to check limit switches using your voltmeter. 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.