Tip & How-To about Heating & Cooling

Furnace Troubleshooting

On some natural or LP gas furnaces, the blower motor has to come on 1st
and then shuts off. This process starts the inital call for heat. If you find
yourself without heat and the blower does not run, turn the furnace to on
at the thermostat.

When changing the fan to on, you are changing the speed, if the heat comes on, that means you have a burnt out speed on your blower motor.

If nothing happens, change the fan speed at the control board.
In some instances they may be using the same blower speed in both the
heat and cool mode.

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1 Answer

keeps giving a code of ops on boiler and will not kick blower on


Are you certain this is a boiler? Furnaces use blowers; boilers do not.

Could you be referring to an induced-draft small blower motor that normally runs immediately on a call for heat?

Is there an electronic control board measuring about 6 inches by 8 inches visible?

We can help if you give us a model # and brand name. Does it operate by oil, natural gas, or propane (LP)?

Feb 02, 2013 | Water Heaters

1 Answer

Ruud Silhouette II Gas Furnace, purges, lights burners and burns until the blower starts and then burner stops and does not really blow very warm air. Once blower shuts off, it starts the process all over again. wont stay on ...just keep cutting off.the flame come on ..then it stop on heat


I would be looking at the heat exchanger. They are designed to have the heat from burnt fuel flow thru them. Cracking or pin holes will let the super heated air into the furnace interior and in there you have some over heating protection some look like buttons, older they look like an external thermostat, and these get the hot gas from the burners and trip then the furnace shuts down. When the furnace comes on again some times the blower will come right on because the sensor says hey this thing is hot when in fact it isn't. This also can and if bad enough will cause carbon monoxide poisoning, please inspect this closely or have a professional look at this. There is no price ever to great to replace a human life.Sorry probably not the answer you wanted but better safe than sorry!

Dec 20, 2010 | Heating & Cooling

1 Answer

When I turn on my furance or ac the blower is always on even though the fan is set to auto. When it is on heat it never gives off any hot air, so it never warms up the house. I had someone look at it and he got the ignitor to glow, but could not get any gas to the unit. He was not knowledgeable of intertherm furnaces. He told me I needed a new gas valve. I read that this furnace has dual gas shut offs. Could that be the problem? If so how do I correct it?


If this is a mobile home furnace they usually have a two stage gas valve. Generally they just have a delay in opening fully and are convertable from L.P to natural gas or vice versa. It is a possibilty that the gas valve is bad. If so it will have to be replaced. First I would have someone check your thermostat to see if that is what is causeing the blower to run . does the burner ever light? I wouldsuggest that you hire a service tech. who is knowledgable on intertherm furnaces. I don't recommend anyone who is not trained to change gas valves,because of safty concerns. I hope this helps you some. Thanks

Nov 12, 2010 | Intertherm Heating & Cooling

1 Answer

legacy heater won't stay light


Hi, Lets see if I can help you out. You have a wall furnace with a forced air fan, 120volts I am sure. It could be a couple of things happening. You say the pilot will light and the burners fire, but after the heat exchanger reaches it's fan on temp, all just shuts down? Does the blower ever come on? It sounds to me that this unit is shutting off on a safety such as the high limit switch.On wall units that don't use a blower, the limit is located in the upper section of the furnace when you remove the cover. If your fan motor never comes on at all, the heat will open this switch and shut down everything.Not knowing if the fan motor is any good, i am just giving you some ideas what would happen if it was bad, shorted, open windings ect.If the motor never comes on then check to see if you have power to it.If you do, then the motor is faulty. If the motor runs, then go to you're high limit. It is a small round flat disc, black wire in and out back to gas valve.Take a jumper wire and jump across this limit and see if it works for you. If so, it would be worth the cost of replacing the limit.If the blower is bad, replace the furnace.Make sure your thermostat is ok also. You can also jump out the stat to see if the unit comes on and stays on. Jump the red and white, you should have only two.If you do this and it runs, do it several times. If all works well, then replace the stat. So there are several things you can check yourself. Please let me know about the blower motors condition. Good Luck,
Shastalaker7

Nov 12, 2009 | Heating & Cooling

1 Answer

my blower motor will not stop running,and my ignitor doesn't light.


I am assuming you are talking about a Natural Gas or LP furnace. The blower motor is powered by a separate 120 volt circuit, so flipping the 240 volt breaker for the furnace will not shut it off. There should be a regular light switch at the furnace that will turn off the blower for servicing the unit. When you take the cover off the unit, there should be instructions on how to re-set the igniter. If it won't re-set, try shutting off the gas for a few minutes, then turn it back on and then reset. If none of this works, and you can't find the owners manual, call a service technician.

Feb 22, 2009 | Electric Circuit Breaker Kit for Furnace

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