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Make sure you have gas pressure to the unit (crack a pipe union slightly) and that the gas valve on the piping and on the gas valve on the unit are turned on. Let me know what you find.
I'd like you to do the things I mentioned so we can make sure we are actually getting gas to the unit (step 1). Then the next step is to measure voltage at the valve when ignitor comes on (step 2).
Set to "volts AC" and put one probe on each of the two terminals at the top of the gas valve (touch metal) right about the time ignitor glows. We're looking for around 24 volts AC.
If you are not getting any voltage at any time, then the board is bad. If you are getting voltage, but no gas, then your gas control valve is defective.
Can you upload a clear picture of the wiring diagram?
Thanks for the diagram. I see this is a modulating valve, which is a bit trickier to troubleshoot than a standard valve. I'm going to open this up to some of the other experts on the site here who may be a bit more familiar with a modulating gas system then I am. Please be patient until another expert picks this up. And please do not reply back as this will send back to me and slow response time.
can you tell me what the red and yellow light does during this time?
then after failure...does light remain the same?
thank you. If you turn off unit and reboot (back on)..is result same
It appears to be board...but I need to know if it trys to cycle or goes to flashing on reboot
You have a bad circuit board. I would contact the contractor..or a Coleman dealer/York dealer and have returned for warranty. There may be a labor charge, but the part should be covered
and fee free to ask any other questions you need....
this unit I have seen as 10yr.