Furnace is fighting a pressure switch issue?


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Old 02-22-15, 10:05 AM
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Furnace is fighting a pressure switch issue?

I have an Arcoaire furnace that is not working properly. When it tries to come on it fails with a pressure switch error indicator. It tries again eventually, fails again, then will sooner or later actually fire up and work if I do nothing. The furnace is about 8 years old and I have never had a problem before. It has been very cold with snow storms here in the past week which is roughly when this started. I opened the furnace up to double check everything it appears fine inside. So it works but it struggles to fight a pressure switch issue repeatedly.

Does anyone have an idea what might be doing this or what to look for?

Model: N9MP2075B12C2
 
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Old 02-22-15, 10:17 AM
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Troubleshooting a High Efficiency Furnace - Pressure Switch


The pressure switch might be bad. That site explains how to test it with a meter.
 
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Old 02-22-15, 11:00 AM
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http://icpindexing.toddsit.com/docum...4001102104.pdf

Is it 2 flashes or 3?

Remove the tubing that connects the pressure switch to the furnace and ream out the furnace nipple with a straightened paper clip.

A backed up condensate drain will also trip a pressure switch with 90% furnaces.

Does the furnace drop out with the burner panel removed?

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Old 02-22-15, 11:55 AM
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Its three flashes. I suspect the switch is fine, its telling me there is a another problem. I do see in my uneducated opinion a lot of condensation in the pipes? So "A backed up condensate drain will also trip a pressure switch with 90% furnaces." could be my problem I think. I'm not sure what you mean by burner panel.

There is a rubber pipe that keeps coming off, see the purple arrow. I keep putting it back on, that could be it. In fact I think the air pressure is pulling it off. Over the years the cheap plastic must have warped or something. In fact the whole rubber tube has probably slightly shrunk which would explain it.

What is the best way to make sure that rubber pipe is secure? This thing here: http://i.stack.imgur.com/PLMCD.jpg ?? I want to replace the metal pressure clip thats used now, it obviously is terrible.
 
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Old 02-22-15, 12:12 PM
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That a hose clamp. That should work. Just tighten gently.

As the hose gets hard.... those metal squeeze clamps don't tighten enough.
If the hose is real hard it may need to be replaced.
 
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Old 02-22-15, 08:56 PM
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Just a long shot, but worth checking; your vents outside are free of snow and/or ice?
 
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Old 02-22-15, 10:18 PM
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Yes, vents outside are fine. I did have a problem a month ago with that which stopped the hot water tank from working though.

My furnace problem is the loose tube, I will clamp it down better soon.
 
 

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