STUMPED .....rheem rcba furnace electrical ignition turns on and then shuts down

[jenrios123]

We replaced the thermostat. Thought the pressure switch was not working and causing it to tell the furnace to shut down but then was told that probably wasn't the case. We were told that if it is a 90% efficiency or higher then it may be the flue or pipes that are clogged and causing it to get to hot and then shutting down. I can't figure out if it is is a 90% or not. Trying to search the model and serial numbers but can't seem to figure it out.
Can someone assist? RCBA-3765GG17XI
Thank you.

[HayZee518]

furnace

there is no furnace listed on the rheem-rudd site that begins with RCBA