I have a Carrier Furnace, model 58ZAV096-16. It was flashing a code 34 but the Heat/Air person that came out did not know what the code was and was not on the furnace itself. He cleaned the rod in front of the ignitors and put in two new filters. This was an intermittent problem with it shuting off in the middle of the night and having to trip the breaker to come back on. It would run for one cycle and shut back off until you trip breaker again. After awhile it would work again. After repairman left, it is now worse and will not stay on. Keeps turning off and now throws a 31 code. Any ideas to get me through the weekend.

Look on the back of the blower access door for the exact code meaning for your furnace.

33 Limit or flame rollout comes to mind.
I would make sure ALL registers are open and the return air is not blocked for starters.

Code 31 has to do with the venting of the furnace. Check the 1/4 rubber tubing that runs to the pressure switch it could be cracked. Also you can check across the two terminals on the pressure switch to see if that it is closing while the exhaust motor is running.

If not those things check the vent itself to make sure it is completely clear. Also where the vent connects to the furnace, take that loose to make sure a bird or something has not falling down into there.