M1MB070AW Pressure switch open lockout problems

Questions about repairs and parts for Nordyne furnaces, air conditioners and heat pumps for manufactured homes including Intertherm, Mac and Miller brands. Click here for Nordyne parts.

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spenceman3000
Posts: 7
Joined: Thu Jan 19, 2012 9:22 pm

Sun Nov 25, 2012 11:30 pm

I really appreciate your help, I am currently having trouble with my pressure sensor. In the last few days my furnace has failed to ignite due to a "Pressure switch is open" failure. It has tripped due to this error 3 or 4 times in the last 3 days. the induction fan is running, but the furnace continues to blink twice indication pressure switch is open. After taking off the cover and messing around with the connections it randomly stops blinking and starts to fire up. I am wondering (hoping) that this is a simple pressure switch failure but I am not sure. I had the furnace completely replaced less than a year ago. I've also noticed a couple times when the furnace is firing up the gas valve clicks loudly 3 or 4 times as opposed to the normal 1 time to open up and ignite the flame.
Worst case scenario, if I need heat desperately (temperatures can get to -40 where I live) is there anything I can do with the wires and/or sensor to bypass this error in the meantime while I try and fix it?

Thank you very much.


DaleM
Posts: 385
Joined: Wed Apr 07, 2010 10:07 am

Wed Nov 28, 2012 1:25 am

Pressure switch is bad. You can try swapping the tubes on it, sometimes that works but only for a while. The make those pressure switches with different ratings. Try to get one with a .18 rating on it. The lighter switch works better when the combustion motor fan blades get dirty and don't move air as efficiently. If you can't find one go with the OEM .20 switch.

In a pinch, sucking and blowing lightly on one of the tubes after you remove it from the combustion motor can get you going. The reason you can't jump anything out is that the control board registers the switch being open at the beginning of the cycle and it's closing after calling for the combustion motor to turn on.

spenceman3000
Posts: 7
Joined: Thu Jan 19, 2012 9:22 pm

Tue Dec 11, 2012 12:43 am

Thanks a ton. I got a new switch installed a couple weeks ago before I headed out of town and its working good so far. I just got the OEM one put in though. Thanks for the help!

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