I HAVE A CARRIER FURNANCE THAT KEEPS LOCKING OUT. I replaced the board, hot surface ignitor, and pressure switch. at each of these points of replacemant the furnance runs fine for about one day. Then I have to , or my wife has to turn the emrgency shut-off to off then to on off-to-on, a few times then it runs for a day or night and then we're back to the same thing. please help!
Have you watched the system while starting to heat? Have you noted what it is or not doing or what it is getting hung up on that is causing the lockout? Have you cleaned your flame sensor? Have you replaced your filter?