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Problem: York Control board problem-Blinking 9 blinks after installation and not working- Reverse Polarity Problem.

Problem: York Control board problem-Blinking 9 blinks after installation and not working- Reverse Polarity Problem

Solution: Just wanted to follow-up…figured out the problem described in my 14 December email…the following may help with future customers who buy this board. As you know, I bought the S1-33102956000 control board for my York P2MP furnace. I installed it and the furnace would not work. Upon installation, I got the recurring nine blinking lights error code which means reverse polarity problem or control board not grounded
Here’s what I found out. Apparently, the polarity of the new, upgraded control board is reverse (in polarity) in design from the OEM control board. To get the furnace to work with the new control board simply reverse two wires when connecting them to the new control board. There are two 24V wires that come from the transformer to the control board. A light brown wire connects to the lead labeled “XFMR” (near the black, blue and red wires and leads)… the other white wire coming from the transformer connects to a neutral lead.

Reverse these two wires…put the white on the XFMR lead and the light brown wire on the neutral lead….and then the furnace will work.

Hope this helps….I like your web site – it has a lot of useful, helpful information; and I plan to order some more parts from you in the future…I think I am going to replace parts before they break…novel idea!

Take care,


*Below we have a real good YouTube Video made by GrayFurnaceMan that discusses problems with reverse polarity in furnaces. Thanks so very much GrayFurnaceMan for making this informative video! I hope this video will help you understand about reversed polarity problems.

36 thoughts on “Problem: York Control board problem-Blinking 9 blinks after installation and not working- Reverse Polarity Problem.

  1. Steve,

    This is very helpful. I am now having an issue with the amber light flashing indicating a problem with the flame sensor. I have replaced the flame sensor as well. It errors with both the new and old. Any suggestions?


    1. Hi Edward! Sorry to hear you are still having a problem with your furnace after replacing the control board and flame sensor. We have a post that addresses this problem on the following page: I hope this post will help you find and fix the problem soon! Steve

  2. Good afternoon!

    I have a York furnace that is flashing red 9 times. The board was recently replaced to a newer version last week. Thing is — the furnace is operating fine. Air is blowing and no issues other than the flashing lights. The previous older board did not flash like this so I’m skeptical that it’s grounding. Any advice would be greatly appreciated before I bring an electrician out.

    1. Hi Eric! I would suggest that you look at the wiring and see if it needs to be changed like it describes in this post. If the wires are correct and that does not stop the blinking then I do not know what the problem could be. Sorry that I can not be of more help. Steve

    2. I got same problem with a new unit. Tried many things and finally the problem was gone when inverting the two power 220V wires. Looks like does not make sense but that was the difference.

      1. Hi Martin! Great! Thanks so much for your post! I hope this will help others out. Merry Christmas! Steve

    3. Mine worked well for a while also, but eventually it will act up and stop working. Do what the post says and you will eliminate the 9 red flashes

      Reverse these two wires…put the white on the XFMR lead and the light brown wire on the neutral lead….and then the furnace will work.

  3. Wow! Just wanted to say thank you! Had the same 9 light issue and tried everything and even reversing polarities everywhere with no luck. Did what you said and i was up and running. So simple. Thanks again

    1. Fantastic! Glad to hear you got your furnace fixed! Thanks for your kind words and letting us know the great news! Hope you have a blessed 2017! Steve

      1. Hey Steve I’m still having the same problem as im looking at all wires connected to the board they are wrong from the motor to board and also to neutral from the chart I have can you upload a picture of your circuit board set up I would really appreciate it

      2. Hi Mr. Juarez! All that I have for the board are a copy of the instruction sheet that we have on the following page: Normally the white wire from your blower motor would attach to one of the neutral connections on the control board. The black higher speed wire from the blower motor would go to the cool terminal and the Blue or Red lower speed wire would go to the heat terminal. If you have any extra wires from the blower motor they would go to park. I do not have a board here that I can look at, but I think this are how the terminals are marked with neutral, cool, heat and park. I hope you can get it working. Steve

  4. Hello sir. had the same problem. flashing red light 9 times. did a lot of troubleshooting , was about to start ordering and buying more parts. read your post, did what you said and shazaam! it worked perfectly! coldest week of the winter. we had bought space heaters for each room and the professional wanted to charge over $500 to fix. thanks for the info! saved me a lot of money!

    1. Hi Derick! Great! Fantastic! I am so very glad to hear that you were able to fix your furnace and get heat for your family! Thank you so very much for sharing your experience! God bless you and your family today and always! Steve

  5. Thanks Had the same problem after lighting strike.

    1. Great! Glad to hear that this post helped you out. Steve

  6. Just wanted to leave my thanks. Installed a new board (in order to save $800 having a ‘pro’ do it) and after installation had the 9 flashing lights, so I googled “hvac 9 flashes” and this was the first result. Reversed the 2 wires and it worked.
    So, thank you very much. You provided a great service!

    1. Hi Josh! Awesome and great to hear that you fixed your furnace and saved lots of $$$! Thank you so very much for taking your time to email us back with the great news! God bless you and your family today and always! Steve A.

  7. HI Steve,

    I have a York 8T series and this morning it didn’t turn on and was blinking 9 red flashes. I am not exactly sure what to do since i have not replaced anything on this. Any help would be appreciated.

    1. HI! If you haven’t changed anything then you might either have a bad control board or a component that is causing the reversed polarity problem like a draft inducer or blower motor. I found a lot about reversed polarity problems with furnaces when I Googled the following: I even see a Youtube video. I hope you can find the problem and fix it easily. Steve

      1. Thanks Steve, I will follow the links and hopefully it resolves the issue.

      2. I hope so. That is a real good Youtube video on reversed polarity from Grayfurnaceman. I hope you can find and fix the problem. Steve

  8. So I haven’t replaced the board and I’m getting the 9 flashes. . What does that mean?

    1. Hi Jon! “Reverse polarity” is a term that describes an electrical condition in which the “hot” wire is connected to the terminal on the receptacle intended for the “neutral” wire and the “neutral” wire is connected to the terminal on the receptacle intended for the “hot” wire. The wires are, in effect, “reversed.” It means you might have a wire that has shorted out in the furnace or you might need a new control board. Most of the time it requires a new control board. I would suggest turning off the furnace at the breaker box and check the wiring to make sure none are grounded out or touching. Best of luck in finding the problem. Steve

  9. Coldest week of the season so far, and our board went out. Found a replacement locally, installed it, and was frustrated that it wasn’t working and was flashing 9x red. Lots of searching and found your post. Reversed the wires, and we have heat again. Thank you. Thank you. A million times thank you. Another night without heat, and I’d be doing some plumbing as well as mechanical!

    1. Hi Jack! Fantastic! Awesome! Congratulations! Glad to hear that our site helped you out! Thank you so very much for taking your time to let me know we were of some help. I hope you have a blessed, warm and Happy New Year 2016! Steve

      1. Thanks Steve. Running into another problem since replacing the board & reversing the wires where they plug into the board-the blower won’t shut off. Do you think this could be related to the polarity change?

      2. Hi Jack! Sorry to hear you are still having a problem with the fan running all the time. I would check between the G and C wires on the board to make sure the thermostat is not telling the fan to run all the time. You can take the green wire off and see if this stops the fan running then you would know it is a thermostat problem or a shorted thermostat wire problem if the fan stops with the green wire removed. I have this problem discussed in more detail on the following page: No, I would not think the polarity problem would cause the fan to run all the time. Best of luck in finding the problem. Steve

  10. Thank You saved me so much time and stress !!

    Give this man a cookie

    1. Thanks Juan! Glad to hear that this post helped you out. I like lots of cookies! Steve

  11. Just read this conversation after looking for help with my York furnace. This fixed my problem and i just wanted to say how much I appreciate the help. This saved us $$ and blessed our day. May God return a 100 fold blessing back into your life.


    1. Hi Mr. Mercer! Thank you so very much for your kind words and blessings! Awesome! Congratulations! Glad to hear that you fixed your furnace! I hope that you and your family have a blessed Christmas Holiday Season! Steve

  12. Hi sir, I replaced my circuit board and it did flash 9 times, I did what you had said with switching the wires, then it started flashing the red 4 times, my blower Motor kicks on as soon as i turn on the power, it did it before I switched the wires also what may cause this, also how does the control board ground to the box, the old one had a ground in the board itself in the mounting screw, please give me some advice

    1. Hi! Four red flashes mean that a limit switch or rollout is open. This would cause the furnace blower to run all the time because the furnace thinks it is over-heating. Please check your limit and any rollout switches to make sure they are all closed. We have a troubleshooting page that I hope will help troubleshoot limits and rollouts about half way down on the following page where I show pictures of limits and a rollout switch: I hope you can easily find the problem.

  13. Thank you so much……….

    1. Thank you so much for your kind words! I hope you have a blessed day and week! Steve

  14. THANK YOU!!!!!!

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