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Does the small vent fan come on and stay running?
OK that is why pressure switch is not closing.The small fan has to pull a vacuum on the switch. Do you have a lot meter for troubleshooting?
We want to see if motor is getting 110 to 110v on call for heat.Check voltage for 115V at the induced draft motor terminals during the trial for ignition. If you have 115V and the motor does not run, replace the induced draft motor.If we do not have power to motor we will go a different route
LOL Typo should say volt meter. Lets unplug wires at induced draft vet motor. Turn thermostat to call for heat and see if we get power between those two wires.
Anywhere between 110 and 120 vac is acceptable.
NO the wires going to the vent motor. There should be two wires going to vent motor.Disconnect them from motor and stick leads into the terminals you disconnected.
That would be great.There has to be a removable connection so motor can be replaced
Follow the white and black wires .There will be a plastic connector connecting the wires .Unplug that connector
Follow them to the plastic connector and unplug connector.See link above
No problem, Unplug and stick one lead into each of the female sides of pug, call for heat,make sure door panel is in place or door switch held in and see if board is sending 110 to 120v to that plug.
OK lets do this.Follow those wires all the way back to control board.Unplug the connector on board where induced draft motor and hot surface igniter plug onto board, Check between the terminal where black connects and the white neutral to see if we get 120v
All neutrals connect together so any one is really fine
Terminals on board this time
OK one more test just to make sure thermostat is not issue, Go ahead and reconnect everything we have disconnected Then on control board where thermostat wires connect. Use a wire, a pair of needle nose or a paper clip and touch the R to W terminal and see if inducer motor come son (Door switch in of course)http://i.imgur.com/JprQdYv.png
OK from all we have checked it appears your control board is failing and will need to be replaced .Immediately upon call for heat the board should send 120 volts out to the inducer unless we have an open limit in which case we would get a 4 flash code.
If you have further questions, please let me know.
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Could have taken a power surge as these boards are susceptible to spikes. Good news is it should be a warranty issue.Parts as well as labor if installed by a licensed contractor.