How timely a topic!!!
I have a 1996 York PM9UP that has been giving me the three red flash issue for a few months. When it 1st happened, I read about it a little, went down and blew out all the tubes to/from the PS and it restarted immediately. The 2nd time it happened, I was on the road for work and simply had the wife shut the unit off at the Tstat and restart it. No problem.
Now it is occurring about every other day:
Unit will start up and fire on low cycle and run fine, but as soon as it tries to go to a higher firing rate, the flame goes out.
Last night, I had to reset it about 4 times straight before it would run OK. Now 14 hrs later, it is still running fine.
Sadly, this install was not typical as I bought the unit new through my father in law (licenced contractor in Vt), who is now retired. The install was done by me, with his help.
I am curious if a simple replacement of the PS will be the solution.