First of lets turn power off to the furnace and allow board to reset then turn power back on and thermostat to call for heat.At that point, tell me if the small inducer vent motor runs?
OK one moment thanks
small inducer fan runs (fan near pressure sensor right?), saw glow igniter on temporarily then gone, still 3 flashes for pressure sensor error
Look with a flashlight real close at glow bar and see if it might have a burned spot like this.
Be right back
Has white powder color like discolorations
Can you set your meter to voltage, Unplug the hoy surface glow bar,Stick the probes of the meter into the plug where you disconnected glow bar.Turn thermostat to call for heat, inducer will start, you will get voltage to the plug,See if voltage continues or is dropping right back out,This will tell us if the ignitor is losing voltage or if it is bad
OK but I will need 5 minutes
After Heater turned on 120VAC at glow bar for 20 Seconds, then sounds like valve opening for gas input, at that moment the 120VAC disappears.
I am thinking you may have a bad ignitor
OK, if thats not it, could it be the pressure sensor or relay on control board? Just wondering for Plan B :)
According to manual, the inducer should come on, pressure switch closes and ignitor should warm up for 17 seconds at which time gas valve will open.I don't think your flame sensor is getting hot enough to send signal to board to open gas valve
Lets try one other thing
Is the little rubber hose in a convienient enough place for you to disconnect it from inducer and leave attached to pressure switch,Turn furnace to heat ,allow inducer to start and then suck on the hose keeping vacuum on the pressure switch so we know it is staying closed?
I think so, One moment.
I did what you said and the furnace fired up! I could here the pressure switch clicking as I inhaled.
OK perhaps the pressure switch or inducer is the culprit here. Take a straightened paper clip and clean the fittings on both the pressure switch and inducer motor and blow through the hose to make sure it is clean and lets see what happens
It's working now (after I cleaned the fittings and blew through the hose and reconnected to inducer and press sw.
Must have been a bit of trash in the switch or fitting
I think we are good to go. Thanks so much, if it fails later I will know what parts to start replacing.
Thanks for allowing me to help