Another question regarding error code '33'.
HVAC1000, you mentioned model ,..I have Carrier WeatherMaker model 58SXC.
Any difference of opinion as to why/what error code 33 is. Does this narrow it down for
a more specific answer? You previously suggested the following.
a) filter- replaced.
b) obstruction- none
c) blower wheel?
d) flame roll-out switch?
I have done the reset, but.. I cannot always guarantee it'll last. Regular check up was done and all seems fine. but,.... it still happens (cold air blowing flame out).

Sorry I do not have any more info. This cold air blowing the flames out has me a bit spooked. Can you take a picture and post it. I would like to see exactly the setup that is on this furnace.

How old is this unit?

If you reset to many times (flame roll out switch) it can loose its internal setting and become weak and possibly easier to trip. FYI

When the blower for the house air circulation is off does it still blow out the flames?

I am thinking of a possible defective heat exchanger. You might think it is the cold air blowing the flames out but if the heat exchanger has a hole in it that can cause the same or similar problem.

If the blower comes on right away after the furnace lights turn the unit off and temporary unplug the blower motor plug so the blower does not circulate air in the home. Then restart the furnace and see if it still blows the flames out or if you see any more or less flame movement that is different when the blower operates. This is not the best way to test for a heat exchanger problem but you have to work with what you have.

NOTE do not run the furnace for a long time in this condition since the blower will not be removinmg any heat. There are safety control that should cut off the burner if it gets to a overheat condition but I never like to stretch my luck if you know what I mean.

Post back to this thread with results.