We have a Weathermaker 8000TS... Generally the LED code is 34 or 14. The gas valve and the sensor have been replaced recently and the entire furnace and filters cleaned. All vents open an unrestricted. The furnace will glow then attempt to light (blue flame)... sometimes it catches, sometimes it will on the second attempt and then finally on the third. When it doesn't, it will shut down for 3 hours then attempt again. We have turned off and on at the power switch to recycle immediately. The blower qill run for 90 seconds then shut off and the light will remain on. The furnace will then attempt to go on again and the same thing starts over, it may catch it may not. Very frustrating.