Luxaire 98% modulating gas furnace installed in 2010. I get an intermittent code for "pressure switch closed", 2 red flashes. This only happens when the temp outside drops below 0. I have found that a bead of condensation blocks the hose to the lower pressure switch. I blow the water out of the hose and then it runs fine. When it's that cold out, I need to run the furnace with the front cover off to prevent the condensation. The hose in question is the square hose with the curl in it.Image may be NSFW.
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