I have a Nordyne M1M furnace that is two and a half years old. A few days ago I turned up the heat on the thermostat and the furnace didn't come on. I looked inside the furnace and the LED light was flashing two times. The legend on the furnace says that two flashes indicate that the pressure switch is open. I bought a new pressure swtich (632453) and replaced it. I'm still getting the same two flashes. Is there anybody there that can tell what the problem may be. PLEASE HELP!! Lee

It could be the line is plugged up that feeds the switch.
It could be a defective new switch.
It could be a defective venter not supplying the switch correctly.

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Originally Posted by hvac1000

It could be the line is plugged up that feeds the switch.
It could be a defective new switch.
It could be a defective venter not supplying the switch correctly.

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Both lines are clear. I can blow through them both. The vent is good. When I disconnect the upper hose from the stack and blow on it the LED stays on constant and the yellow LED comes on and the furnace ignites, but as soon as I quit blowing on it the yellow LED goes out, the flame goes out and the furnace motor quits a while later. When I disconnect the lower hose and suck on it the same thing occurs. Is this then a bad 'new' pressure switch?

I found out that my problem wasn't with my pressure switch (although the LED light was flashing two flashes indicating that there was a problem with the pressure switch). The inducer motor wasn't kicking on first to let the pressure switch work properly. Thanks, though, to hvac1000 for his input to the problem I was having.