Well my HVAC repair story goes like this; I will start from the end:
If the issue was intermittent prior, but now is simply all the time. What should I be looking at and what am I going to screw up. If I have to get another HVAC tech in I will have the urge to take the first guy to small claims because his wife is a total piece of work and I don't want that hassle. I promise I am not touching gas, I like my house in one piece and I am good with electronic repair and some mechanics but that is all.
13) The install manual says: Locate and correct gas
interruption.
• Check front cover pressure switch operation (hose, wiring, contact operation) Correct if necessary.
• Replace or realign igniter.
• Check flame sense signal. Sand sensor if coated and/or oxidized. <I ran some (extra?) fine wool over it.
• Check flue piping for blockage, proper length, elbows, and termination. <looked good.
• Verify proper induced draft blower performance. < the tech did strip some wires to tests this ?!)
12) So, the unit goes/went so far as sending 24V to the gas valve BUT there is no smell of gas at all and no ignition (rod gets bright yellow etc).
11) Yes, I likely have to take them to small claims court but need to fix the furnace before I do that; if I do it no cost or an inexpensive part I don't have to worry about that. They can live with the review.
10) The problem turns out to be that the HVAC tech that took my 20" channel locks with them and wouldn't acknowledge I took them or even give me a call about them for 2 days with his wife running interference has bailed either because I embarassed him or because he is whooped by his wife this seems to want to go beyond the scope of handling the office stuff and co-ordination.
9) After I posted a review on google that got my 20" channel locks back. I didn't say they stole them but I did give a clear and accurate description of events and his wife that answers the phone (woooo weeeee!!!).
they won't finish the work that I paid for because they are upset with me. If posted that they stole the tool I might understand but I didn't; I did skewer the HVAC techs wife that answers the phone and how she conducts business (it was bad).
From the start.
1) Intermittently my Goodman GME95 (10yrs) would not fire up. It would fail after 3 times (one flash)
2) Did a diagnosis and got as far as the gas valve getting 24V but not opening; two of the times I gave it a tap over the next week it started up fine but did not go further.
3) Local HVAC Goodman company raised a couple of redflags but I was too tied down on time. They have at least 20 techs in 8 locations; did the original install and have good google reviews. Still red flags from the phone attitude and something odd they said too.
4) I was not able to get a quote for a gas valve because they MUST do the diagnosis, that I get but not even a quote on a type of repair for a part they have?
5) Regardless, they came over. Took my word on what I did and I was able to get a quote.
6) They did a couple of other checks on repair day and replaced the gas valve.
7) The furnace was working at the time; but intermittent and they proceeded.
8) They unit worked for a couple of days then nadda, nothing not even intermittent. One flash.
The fact you measured 24V at the gas valve while the ignitor was energized would seem to indicate a bad gas valve.
I would test the pressure switch to make sure it's not opening intermittently.