Furnace will not turn on. Pressure Switch issue


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Old 03-03-14, 02:45 PM
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Furnace will not turn on. Pressure Switch issue

Hi guys, my furnace is not working. The only way I was able to get it to work was to pull the purple wire off the pressure switch and then it turns on and operates normal and then a few hours later the problem occurs again; and I have to disconnect the wire to get the furnace working again. I have tried pulling the two hoses the connect to the pressure switch but it will not make the furnace work unless I blow in the hose then the furnace will turn on.

Can someone please tell me how I can get my furnace to function normal. If you need more information let me know.

Thanks
 
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Old 03-03-14, 03:23 PM
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How about giving us the make and model of your furnace. I personally am not familiar with two hoses being attached to the pressure switch.
 
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Old 03-03-14, 03:27 PM
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The furnace is a Lennox G43UF
 
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Old 03-03-14, 08:19 PM
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Lennox manual suggests checking the pressure lines as well as the attaching points for obstructions. A little "crud" in the lines or the attaching nipples on the switch and inducer can cause the problem you describe.
 
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Old 03-03-14, 09:37 PM
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With the cold weather it is very possible that you have a blocked or partially blocked vent/flue line from your furnace to outside due to freezing condensate. The job of the pressure switch is to make sure those lines are not blocked so that you don't get a backup of fumes and CO in your house.

Like Woody mentioned..... you also need to make sure that the pressure switch lines are clear. Especially check the locations on the inducer blower where they connect. Those little fittings can become blocked with condensate.calcium causing issues like you're having.
 
 

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