I have a Rheem AC/ Gas furnace unit, located on the roof, of a rental house. Both the electricity and the natural gas, had been shut off. When both were turned back on, the gas furnace won't work. I took off the service panel, and the led light on the circuit board, flashes 3 times, hesitates, then flashes 3 more times, over and over. Does anybody know what this code could be. Could this be an ignighter code?

Any help would be appricieted,. Thanks... Jim

Usually 3 blinks mean something to do with the pressure switch or the venter end switch. There should be a legend on the door panel of the unit that describes the number of blinks.