Gas and Oil Home Heating Furnaces - Diagnostic Code says "hi-limit opening"?

I have a Bard DCH085D60C from 1998. It is LP and I noticed the furnace is off when I come home sometimes. The amber code light is flashing 3 or 4 times and the code key says it is due to high limit opening. When this occurs 3 times it goes into a "hard lockout" and I have to flip the electric breaker to get it going again. Seems to occur intermittently but never know when it's going to shut down when I'm gone. Does anyone have any info on what to do about this?

Thanks!

That limit switch opens when the furnace overheats. I'd start by checking to see if the furnace filter is plugged, followed by checking to see that the cold air return is not covered over and that all the warm air vents are open.

Besides what was said, -

Also check to make sure blower motor spins freely by hand. REAL freely.

And that the cupped vanes are not filled flat-shaped by lots of caked-on dust.

And that the blower always is still going when you notice the limit trip, in case there is some malfunction with the motor.

Also if you have central A/C and neglected filter changes, or merely used cheap fiberglass filters rather than paper pleated ones, you may want to access a/c coil above furnace, if you have that, to see if the coil fins are clean enough.

Or, if you have higher than Merv 5 filter in there, switch to just a MERV 5 pleated filter.

Thanks for the helpful information. The home has been empty for several months and the furnace was set at 50 degrees. Now we are living in the home, we set the temp at 70 and it seems to be having a hard time keeping up.

I'll try the suggestions and see what happens...