Carrier gas furnace will try to start, but igniter does not light furnace. Red light in window flashes -is thiis the "code" for the numeric list on the attached plate?

Your thermocupler could be bad.

Sounds like a thermocoupler. Just had this happen to my 1960 lennox.

The light is the code. 3 blinks with a pause and then 4 blinks = code 34. The code info should be on the furnace door.