Frigidaire ( Nordyne ) Gas Furnace won't start

I have Frigidaire/Nordyne furnace model L1RA 090C-16. The furnace starts the inducer, the ignitors glows then the gas valve clicks on and right back off immediately. Then I get 3 flashes from the status LED (pressure switch stuck closed). I have checked the pressure switch and it is working ok. If it wasn't, the inducer wouldn't start. I have checked the voltage at the gas valve and it comes on and off so quick my digital meter won't read it. I have changed the gas valve and it does the same thing. I also checked my 24volt ac to the control panel and it is rock solid. Incidentally the furnace will come on every now and then. I am considering changing the control panel the part number is 903106. Thanks for any help you can give me.

 

The inducer motor is typically not controlled by the pressure switch. The pressure switch is there to verify that the inducer motor and the venting system are functioning propelry, and to only turn the main burner gas on if the venting system (inducer motor included) are working properly.


So go back to examining the pressure switch and the venting system. That's where your problem apparently is.


A competent repairman would test the pressure differential across the pressure switch inlet and outlet with a manometer to determine whether the pressure switch is bad or there is a defect in the venting system.

 

The book that came with the unit states that if the pressure switch is stuck closed, the inducer motor will not run. Status led will simply blink 3 times. If it is stuck open it will come on see the open switch and stop start up sequence and blink 2 times. My unit goes through the entire sequence until time to pick up magnet valve on Gas Valve then clicks on and right back off. The unit will then try to keep starting over and over. It never locks out. I took the inducer motor out checked for an obstruction in my venting system. All looks ok. I checked the tube going to the pressure switch and it is ok. I also barely sucked in to the tube and checked the switch with an ohm meter. It is working ok?

 

Control board fixed it.