Have a Carrier Model 58STA furnace with status code 33.
It's about 8 years and the 1st row will ignite (usually) but not the 2nd & 3rd rows. If I fan them, they will ignite. Tried the basic stuff in the manual and it ran OK last night. Today tried to clean a bit better, back to the above. Replaced filter, checked all connections, blower wheel is not loose and it is not windy out today.
E are however in the greater NW suburbs of Chicago, 0 degrees now and -5 last night, so not good timing. Any ideas how to isolate what's left; IE: switches, roll out switch or blower motor? Thanks in advance, Charlie

Pull the burners and clean out the orifices. Fanning tells you that you are not getting enough gas flow to ignite the tubes.