Can't find all the limits in the safety circuit? Has the board failed? Use this strategy to quickly and easily identify if there is an open safety/limit or a potential faulty board on a furnace.
My Bryant 915SA48080S17 is heating up but throws a 33 after 3 minutes. The filter is brand new, and I even opened up the blower door, but the 33 is still popping. Any suggestions?
If it’s within 3 minutes and filter is clean, registers open and such…I would think dirty secondary HTX or gas pressure. Many items affect limits, but tripping in 3 minutes eliminates a lot. We have seen issues with insulation not allowing proper airflow around the limit…but it runs longer than 3 minutes. Could be faulty limit but that’s rare. My guess would he dirty secondary or something blocking airflow. Any checks beyond filters and registers should be performed by a trained professional. I do a lot of DIY work myself, but replacing a trap on the sink won’t burn the house down as an example. Not knowing your skill level, just making sure that’s clear. Good luck.
