I have a Bryant Model 397H. Have had an intermitent problem for the past 3 years. Furnace starts normally, burners come on and in about 5 seconds go off. This can repeat two to three times before remaining on and running normally. I have had two repairmen out to look at it and both times it would not malfunction when they were standing over it, go fiqure. Have see n lots of problems with the gas limit switch online, could this be the problem or mayby in the board. Furnace is clean, new filter, furnace is on propane. Any sugestions out there?

If your unit has a flame sensor try removing it and cleaning it or better yet by a new one and replace it. This is a common problem.