My luxaire furnace won't fire up. When I open the bottom panel and flip the pressure swith over and over, it tries for about 1 second to run

Exact model number of furnace?

Mdl# g8t11516uhc11a
s/n# ekjm466306 when I flip the pressure switch on and off repeatedly, it tries to start up for a split second
Thanks

I think you are referring to the interlock switch behind the blower access panel. The pressure switch is typically connected to the draft inducer via a small rubber hose. Sound right? Try this: Pull one of the wires off the PRESSURE SWITCH, then try to start the unit again. If it runs longer than before, the P/S is stuck in the closed position. Are there any status LED's on the unit?

I did mean the switch behind the access panel.
When I flick it on and off, it sometimes tries to start for a split second

The interlock switch is interrupting and restoring the power supply when you disengage and engage it. Did you... try... my previous suggestion?

There is a red status light behind the access panel and the guide says if flash once then off then lockout caused by flame sensed... when there should be no flame

Does the flame ever come on?

No flame ever

Check flame sensor circuit for short to ground. Check circuit board for evidence of exposure to moisture (odixe trails, circuit path bridging).