i have a G-UA024514B that i don't think is more than 5 or 6 years old. came with the house. last night i herad it kicking on and off repeatedly and felt cold air coming from the vent. the diagnostic light flashed 8 times indicating a bad gas valve or low gas pressure. anybody know how i can test the valve to see if its bad? or better yet, anyway to fix it if it is?
Couldnt find the error code manual for your exact furnace but on other silmilar models a code 8 says ignition failure. If the burner is cutting in and out, try cleaning the flame rod with light sand cloth and reinstalling it. It is usually a small rod located on the left side of the burners with a single wire going to it. Just be careful if it has a porcelin base not to damage or crack it. Very common problem.