Lennox Furnace


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Old 11-10-13, 12:09 PM
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Unhappy Lennox Furnace

Woke this morning with No Heat, Thermostat seems to be set correctly,Clicked off Summer switch briefly then back on,the vacuum fan comes on for 3 seconds then off,getting 2 GREEN LIGHTS flashing on Circuit Panel,,,Any Help out There?
 
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Old 11-10-13, 12:16 PM
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To better assist you, please post the model number of your furnace. From your description it sounds like your pressure switch is not closing. I suggest you remove the hose between the inducer motor and the pressure switch. Make sure the hose is clear and has no blockages from end to end. Also check the port where that hose attaches to the inducer motor. Sometimes debris gets in that port and the small amount of pressure isn't able to close the pressure switch which in turn allows the ignitor to energize. You can use a paper clip, a small drill bit or allen wrench to make sure that port is clear from the opening all the way to the fan blades. Once you have cleaned blow into the hose to verify the port is clean and air is able to get through. A lot of times this simple procedure will correct the issue you are having.
 
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Old 11-10-13, 12:32 PM
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80 uhg 3/4-100 (100,000 btu) 80%
 
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Old 11-10-13, 12:39 PM
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Will Do,,,Thanks!!! Dawg
 
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Old 11-10-13, 01:07 PM
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Did as You suggested,,hose is clear and can hear the diagram working as I blow in and out.Hmmm?
 
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Old 11-10-13, 01:16 PM
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Did you clear the port on the inducer motor? Here is a link to some info that may be of benefit to you:

http://hvacpartsshop.net/80UHG_Series.pdf

Check page 31 for troubleshooting tips for your issue.
 
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Old 11-10-13, 01:47 PM
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Yes,,All Ports are Clear. This just happen over night so thinking something electrical my have failed. Thanks for the Link!
 
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Old 11-10-13, 02:13 PM
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I suggest you inspect the flue pipe to insure it is not blocked or restricted. Sometimes birds, insects, leaves and etc. find their way into the vent pipe and will prevent the pressure switch from closing. You can temporarily (just for testing purposes only) disconnect the flue and see if the furnace will operate.
 
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Old 11-10-13, 02:41 PM
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10-4,,,I'm on it as I type!
 
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Old 11-10-13, 03:21 PM
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Disconnected Flue from Unit,,,same problem,,must be Pressure Switch,,this Unit is 13 Years Old and have never had a problem with it. Thanks for all your input!
 
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Old 11-10-13, 03:33 PM
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Here is a quick test to see if it might be the pressure switch. Remove the two wires from the pressure switch. Use a jumper wire to connect these two wires or if they are long enough you can just connect them together. The pressure switch needs to be open for the control board to send voltage to the inducer motor. So once the inducer motor starts spinning you will connect the two wires together as quickly as possible. The best method to do this is to use a short piece of wire with alligator clips on each end. If the furnace functions with the pressure switch circuit closed then it is time to replace the pressure switch.
 
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Old 11-11-13, 07:17 PM
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Unbelievable,,,turns out it was just a lose wire that I had connected to the New thermostat about a year ago! Don't really know why it would just come lose now? Thanks for all your Help,,and "THANK YOU" if you are a Veteran !!!
 
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Old 11-11-13, 07:32 PM
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Glad to hear you found the source of your problem and thanks for letting us know the outcome.
 
 

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