I have a Luxaire high efficiency circa 1992. I'm not getting a fault code from the control board, but can't figure out why this thing is acting like so. When it calls for heat, the main blower turns on and stays on. The venter motor may or may not kick on. If it doesn't, the hot surface ignitor will not activate and the gas valve won't open. This is an intermittent problem. Sometimes everything happens and cycles several times. When stat is satisfied, evrything shuts off at once. Then the cycle does or doesn't start all over again. If it stops, the main blower remains on indefinitely and will not attempt to refire. I know from prior experience that the ventor motor should kick on first and when stat is satisfied, the blower usually will blow for a few after burners kick off right? Any ideas?

Check circuit board for DIP switches, and/or any evidence of exposure to moisture (green trails). The switch contacts can oxidize over time, and "confuse" the board. If present, make sure they are set correctly according to the service label and/or the installation guide. Try toggling each one a few times to "scrub off" the contacts, but assure you return each to the correct position. If that doesn't work, try bypassing the thermostat (jumper "R" and "W" circuits together) to see if mental health is restored. Aside from that, it sounds like a faulty circuit board.

The fact that you are not getting any codes may mean this is a power issue to your inducer motor. Perhaps not being trigger from the control board due to bad board, perhaps something in the wiring to the motor, or maybe a dead spot on the motor/bad motor.

If the control board is a White Rodgers go here for troubleshooting guides (http://www.white-rodgers.com/wrdhom/common/ptech/furnace/furnace_02.htm).

Intermittent problem can be the hardest to diagnose. Let us know what you find and maybe we can give other ideas.

If you call for heat and the inducer motor is not running but the blower is-- with out a code on the furnace. The thermostat is bad -- a bad connection 24volt side, wrong thermostat or wrong thermostat configuration.

If you call for heat and the inducer motor is not running but the blower is-- with out a code on the furnace. The thermostat is bad -- a bad connection 24volt side, wrong thermostat or wrong thermostat configuration.

Yes, that is something to check into. The tstat may be erroneously running just the blower and not energizing the furnace. Next time this happens check you G and W terminals at the tstat.