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Hot Air Furnace - How to Troubleshoot the Blower

The furnace is hot and every once in a while the burner will come on for a short time and then go off again. But the blower that should be running to circulate the hot air from the furnace to the house is not working. How can you fix that? It really isn’t very hard.

It does not matter what the fuel of your hot air furnace is. If the blower is not circulating the air through the heater then you are not getting warm. The function of the blower is to move the heat from the heater to the space that need to be heated.

A few simple tests can tell you what your problem is. Do you have power going to the motor that runs the blower? If you have power going to the motor and it is very hot than maybe the blower wheel has come lose and it is stuck on something that is keeping it from turning. Try to turn the wheel to see if it is stuck. If the wheel is not hitting anything and just turns hard then the bearings of the motor are bad and the motor needs to be replaced. In some rare cases the motor has little tubes to the bearings and some oil can be worked into the bearings to free them up. This is a long a tedious process, but I have done it successfully a few times.

If the wheel is hitting something, then try to see if it can be fixed. Sometimes the set screw will just come lose from the shaft and repositioning the wheel and tightening the screw will fix the problem.

Sometimes power will be going to the motor and nothing at all is happening. Replacing the motor is then the only option. The worst case that happens and is one of the most common problems is for the hub of the blower wheel to brake off. This lets the inside of the wheel fall down on the motor shaft. The metal from the wheel will saw off the shaft of the motor rather quickly as it is spinning trying to run the blower. The result of this is a ruined wheel and motor.

This gives a brief overview of some of the many things that may happen to your blower in your hot air furnace. I have encountered many other things over the years, but these are the most common problems. It will give you a few things to look for if you are having problems. Be very careful because many times the edges of the metal pieces are very sharp. You can be cut very easily when checking or handling these parts. I know and have the scars to prove it! Do not be in a hurry and be safe.

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coleman evcon furnace


How old is your furnace? Does it have a circuit board that controls everything, or are there separate controls for each function?

Nov 19, 2013 | Heating & Cooling

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

2 Answers

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. Will do this several times. And some times it will work fine, burner will stay on once blower starts and heat just fine? Any thoughts on possible issues?


Flame sensor needs to be cleaned. turn off the furnace power switch or breaker. pull the flame sensor located in the burner runner section of the furnace. It will be easy to locate because it has 1 wire running to it. pull the screw being very careful not to harm anything else. get the sensor out. inspect it for cleanliness. clean the sensor with light grade sand paper gently. re-install the sensor plug the wire back on. restart your furnace and this should fix the problem.
CookHVACR

Nov 19, 2010 | Heating & Cooling

2 Answers

Ruud furnace Model URKA A030jK08 Code opt 589


Flip the lower panel over and look for a wiring diagram. On that diagram there will be a diagnostic chart. Let me know what 5 blinks represent. Then I want you to read on.

On a call for heat, the 24 volt thermostat sends a signal to the control module. The control module will indicate a call for heat with a light on the control either blinking or remain solid depending upon model. The inducer (exhaust) blower will purge all gasses from the furnace and pressurize a pressure switch. Once the pressure switch tells the module to continue, the electronic ignition will energize and send 120 volts to the igniter. The igniter will glow and you will be able to see it if viewed thru the small inspection port. Once the igniter gets hot enough, it sends a signal to the module opening up the gas valve (24 volts). Either a pilot will come on or the burner tube will ignite then spread the flame to all burners. Lastly a safety sensor will be looking for a certain temperature within a few seconds and the furnace will continue to operate and the room air blower will turn on in a minute or two.

What could go wrong? The unit will not run if there is no signal from the thermostat (bad thermostat or broken wire), the control module does not sense a signal from the thermostat (bad control), the inducer does not energize (bad motor), the pressure switch does not close (blocked vent piping, bad switch, plugged condensate hose), the igniter does not energize (bad control, bad igniter), the gas valve does not open or there is no gas (bad gas valve, broken wire, no gas), the pilot does not light (dirty pilot), the burner does not light (bad burner, plugged orifice, not enough combustion air), the flame does not spread to each burner (bad flame spreader, dirty flame spreader, more bad burners), the flame safety sensor does not detect flame (dirty or bad flame spreader, bad flame sensor, broken wire, bad control), or the room air blower does not energize (bad fan motor, bad control).

Nov 23, 2009 | Heating & Cooling

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