I have a Carrier gas furnace model 58PAV. It stop working two days ago. I turned the power switch off/on it started runnung then fire was lit up and burning for a few seconds then stop. it would re-try 3 times and stop. The LCD dignosis codes is 34. Checked filters and it seemed OK.
Your help is very much appreciated.
I suspect you have a fouled flame sensor. This is something you can correct yourself. You will find the flame sensor in the burner box. It will be located on the opposite end of the burners from the glow bar ignitor. It will be a metal rod that sits in front of the burner. The rod will be seated in a ceramic base and is attached to the burner box with one screw with a 1/4" head. You need to remove this sensor and polish it with steel wool, scotchbrite pad or in a pinch sand paper.
DO NOT confuse this with the glow bar ignitor as cleaning the ignitor will damage it.
Thank you very much for your reply, SKIP4661.
You're right. The flame sensor could be the problem. One of my friends told me the same thing. I swapped the flame sensors from the other heater(I have two zones) it's still not working. My friend told me the circuit board may be bad so I swapped the circuit boards and it works. I have to replace the circuit board.
Once again thank you for your help.