[jubrand]

I have a Bryant plus 90 that's about 10 years old or so too. I've had some of the same problems you guys are talking about. Basically, the burner would fire and burn for about 10 seconds, then shut off. It would try 2 more times before it gave up and locked out for 3 hours.

We originally thought it was the flame sensor, then the gas pressure. None of that seemed to work. FINALLY, the tech (oh sorry, the THIRD different tech), realized that the wiring harness that connects the flame sensor and other burner components (sorry for being basic, I don't know too much about the wiring) was faulty. He replaced the harness, and that fixed it. You might want to check it. In my case, it was just one wire that was pulling out.

Now on to my NEW problem.......For the last week, the furnace can't seem to get the temp up to the setting on the thermostat. the thermostat (Honeywell digital with four time zone settings...wake, leave, return, sleep) will call for heat, and the burner will fire up and burn as it should. But, after about 5 minutes or so, the burner shuts off (blower is always on), even if the proper temp hasn't been reached. The thermostat still looks like it's calling for heat (small flame icon is showing). Sometimes, the burner will fire again, but most of the time it stays off. If I cut the power to the furnace (by opening the front cover to trip the safety switch, or by just flipping the power switch on the side of the furnace), it seems to reset something and upon turning back on, it'll fire the burner again and repeat the same process.

I've got the LED error codes on mine, and it's giving me code 33 after the burner shuts off. That corresponds to "Limit or flame roll-out switch is open".

Does anyone have any ideas??? I'd like to figure it out myself and fix it rather than pouring more $$ into techs coming out. Could it be the thermostat that's broken instead of the furnace?

Any help is extremely appreciated.