I have a 14 year old Payne Upflow gas furnace. The furnace is in the attic and will nt work when the temp. in the attic get somewhere below 60 deg. The system shows and error code 31. Which is supposed to mean the there is either a defective inducer motor or start capacitor. I replaced the start capacitor two last year, so I don't think it is that. If it is the inducer motor why does it work when the ambient temp is above about 60 deg? Is it possible that this code is not correct and that is maybe a faulty electronic control board. The reason I say that is that at times I can move some of the wires an the system comes on other times it will not. I am really confused and don't want to buy one replacement part and actually need a different one.

Your question is difficult to answer. It could be the small inducer motor or the capacitor for the inducer motor if so equipped the inducer might not want to spin at lower temps. Since it is temp related I would get a can of component freeze from Radio Shack. They use it on electronic circuits. You could spray it on some of the components when the unit is running and it might cause a shut down since you will be spraying a very cold product recreating cold conditions that the unit does not like to run in.

OR you can trace wires down until you find one that has a loose connection since when you moved the wires the unit ran.