Goodman single stage gas heater intermittent问题 续

https://bbs.wenxuecity.com/fdcj/1878970.html

Changed gas valve and it has worked close to 2 wks now. 

intermittent HVAC problem is annoying. When no time pressure to get it fixed, it is like playing puzzle game. 

I read more intermittent HVAC problems on reddit. One got my attention. A screw is not tightened 

good enough at AC contact and caused tough intermittent HVAC problem. An extra 0.5 ohm resistance could cause quite a bit heating at 40A (or 30A) I^2R and it could oxide the surface and increase the resistance. 

 

Here is one puzzle. Not my posting. 

https://www.reddit.com/r/hvacadvice/comments/1rm5184/goodman_furnace_igniter_glows_26vac_at_gas_valve/