New Suburban Furnace Issue Problem also with Suburban

[Cliffy]

We have a 2019 TT and problem has cropped up with the furnace. Let me preface this with the fact that I have been a mechanic for 55 years and I was a certified swimming pool heater technician in an earlier life so I know gas fired equipment.

The problem really is with Suburban warranty services. The problem with the furnace is that when the outside temps get down below 40 degrees the furnace will start and run fine the first time the thermostat calls for heat. Once the TT warms up the thermostat shuts down the furnace. Now when the thermostat calls for heat again the furnace fan runs (first as it should) but then the furnace shuts down in 10 seconds and goes into "lockout" mode just as IF it had tried the required 3 times to start and couldn't get going. If I recycle the thermostat by removing power from the thermostat to the furnace (as is called for to recycle a "lockout" condition), the furnace will run just fine the first time. Then the shutdown happens again on the next heat call.

The furnace never gives itself 3 tries to start (which should take about 2 - 3 minutes). The only place this could happen is on the control board circuitry for the restart system. No where else. If it was the sail switch it wouldn't start on the recycle try. if it was the overheat switch it wouldn't start on the recycle try. It has to be a board level problem.

Now the real issue. I've had a long conversation with the tech at Suburban and he agrees that it probably is a board issue BUT they won't send a board unless a "service center" can duplicate the problem. It won't get that cold anywhere near my home until January and only at night but it gets that cold where we go camping all the time. And, no technician is going to work late at night to see the system fail.

A real "catch 22" !

I'll probably wind up ordering a dino board and put it in myself rather than try to get warranty on it just so I don't have to be up all night operating the furnace.

Any other ideas out there?

[okcnewbie]

It sounds like you nailed it IMO. If the dino board isn't too pricey I would probably go that route as well.
I don't think you gave the model but if all it takes is connecting the two blue wires to turn on the furnace I would probably try that just to eliminate the stat/wiring. Probably the board. Have you tried reseating the connector already.