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Replacing controller on lennox furnace


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  • Replacing controller on lennox furnace

    I have a new lennox control kit I am putting on a lennox G20RE furnace. It is replacing a Johnson Control. The wiring is marked differently and I understand where each wire must go on the new unit, however there is one 'wire' that I have a question on. It has to do with step 10-h if you know the instructions which reads:

    h- "Attach the provided insulated 1/4" quick connect to the Johnson pilot red spark wire and connect it to the ignition control terminal 9-Spark."

    The problem is, when I pull the 'wire' off of the spark electrode on the Johnson, it doesn't even appear to be a wire. It looks like a wire, until it pulls off and then it looks like a tube that fits over a small tooth-pick size barbed metal protrusion. I can't see any indication of a metalic wire inside the 'wire' that I pulled off. I tried to pull that 'protrusion' out with some long-nose pliers, and it doesn't seem like it is made to pull out. (It is recessed completely, so I can't see what it is at all.) This 'wire' is clearly made to connect to a spade plug on the new controller, but I'm not sure if the 'provided insulated 1/4" quick connect' is a wire connector either. But the spade plug recepticle (male portion) which is part of the controller is clearly an electrical connection.

    Can anyone tell me what this 'pin' does? And what it needs to make this connection. It is very hard to describe without pictures so if you know this kind of stuff, I could go in more detail if necessary.


  • #2
    it is a carbon filament inside a high voltage wire. the center conductor is a carbon fiber inside a red colored high voltage insulator. if you cut the wire and push it into the round connector with the barbed tooth pick it will make up the high voltage connection. the round thing with the toothpick is the high voltage tower.


    • #3
      lennox johnson controls

      They have lots of problems with those controls. We replaced with honeywell 1003 spark control. I have replaced 100's of them.


      • #4
        Thanks for both replies

        - Good info - thanks. I figured it was something like that but didn't know those terms you used. So to be sure, what I described was the old control. On the new one, I need to hook up the carbon filament wire inside the high voltage insulation to a male spade terminal. They supplied the female spade terminal as well, but on the receiving end for the carbon filament is a small female pin size hole. I guess I strip back the insulation to get to a 1/4 inch of carbon filament and solder it in the spade plug? Is that correct?

        One other issue I am having is that they also supplied a new pilot sensor. I presume it puts out a different voltage than the old one so I do need to replace it, but getting to it seems a bit of a hassle. I removed the damper cover and door and can reach it, but can't budge the spade plug off of it nor see how it is mounted. Next step is I'm going to try to remove the burners so I can actually see how it is held in place. Please let me know if this is the wrong thing to do!!

        Thanks again for your help.

        - That's what I was told when I described my symtoms so I felt that it was worth the 'do-it-yourself' chance of buying the $130 part. It seemed pretty sure. Didn't know just a part replacement could leave me with these questions though...


        • #5
          flame sensor and hv wire to spade fix

          Yes that is right about the hv wire to the 1/4 in spade. Also the flame sensor
          Rod is hard to get out. Ceramic with a metal rod in center. I bend the spade back so you can pull it down and out also you can just clean yours with steel wool and that works also. I have left some in flame sensors and just cleaned and had no problems
          Safe thing to do is to clean sensor. They break very easy fyi...


          • #6
            what I've done there is use a piece of a sharpened paperclip wire, terminated in the spade connector and shoved the sharpened end into the high voltage wire about an inch.


            • #7

              Thanks to both you guys. I have a working furnace tonight. Input from both of you was helpful.

              Thank you very much.