Bryant 90 plus code 33 - limit circuit fault

[animaldoctor]

I've got a Bryant 90 plus furnace and it is giving error code 33 for limit circuit fault. The fan works but we are unable to get the AC to turn on. Was giving code 13 - limit circuit lockout until I shut down all power and waited a few minutes in an attempt to reset the system. Changed the filter, it was dirty. Does anyone have tips on troubleshooting this further?

[Freon]

When you call for AC, does the outdoor condenser run? If yes, carefully feel the 2 copper tubes exiting the condenser. The small one should be warm to the touch and the larger cold... are they?

Is this error happening when you are only calling for AC? Have you had any bad electrical storms or and electrical work done on the house?

[animaldoctor]

The outdoor condenser does not run. It had been running fine all summer, we turned it off for a week or so of colder weather. When we turned the ac back on it did not produce cold air and the outside condenser does not run. I will try turning the thermostat to off and see if I still get the error. No recent electrical storms or work done recently. Thanks Freon!

[animaldoctor]

I found the limit switch on top of the combustion chamber, pressed the reset button on it and now everything seems to be working correctly. Also replaced the filter, it was dirty and from what I've been reading it sounds like that could have caused this error code in the first place.

[Freon]

Poor air flow through the furnace caused by a dirty air filter or closed/blocked return and supply registers will cause the heat exchanger to overheat thereby tripping the high limit safety. Changing the filter and keeping the air flow strong will make your heat exchanger happy and your furnace more efficient.

[animaldoctor]

Thanks for the tips Freon, is there any additional maintenance that I could do to keep things running well? No routine maintenance has been done in years. Thanks again for your help!

[Freon]

Filters are the easiest and most important. Without adequate air flow you stress the furnace.

You can check the blower motor and blower wheel (squirrel cage) to be sure they spin (by hand) freely and quietly and the blower wheel isn't covered in dust. Depending on the location of the furnace you might want to clean the heat exchanger. This job can be tricky especially if you don't have easy access to the heat exchanger. If it's an old furnace you may want to have the heat exchanger checked for cracks.

[animaldoctor]

awesome, thanks again Freon!