Can anyone give me any insight into the normal operation of a Carrier
> three wire pilot. Assembly was recently replaced with a new pilot
> because it would not prove pilot flame and thus burner would not fire.
> I believe it is supossed to cut out spark after pilot flame is proven
> . Burner is now operating but spark ignitor is not cutting out. > Thanks in Advance,
> John Taylor
I have worked on these 3 wire pilot assemblies for years. They are inherently flawed in their design and very unreliable. Both the LH680005 and other clones use the same design. I have taken these pilots apart and they all rely on a springy copper metal piece to precisely contact the pilot contact and later on the main burner contact at the precise time. If the pilot keeps ticking through the whole cycle it means that the contact internally for the pilot is still engaged because the springy metal has changed slightly internally and thus not breaking contact with the spark box. The other thing I have found is the warp metal that controls the warp switch on the other end often can change slightly in even 2 to 4 weeks and supply too much gas right away to the main burners which causes a major explosion when the main burners are turned on and initial ignition takes place. There is no way I would recommend to anyone that they can take these pilots apart and repair them. If you open the pilot valve to increase or decrease the pilot flame you need to disconnect the 1/4" aluminum pilot line from the pilot and reconnect it before you run your furnace again or otherwise there is a high probability that the furnace main burners will again explode when ignited. The better idea would be to get a new furnace which does NOT use this 3 wire pilot as it is totally flawed in its design.