We have a problem with our gas central air unit not heating... called a repairman he told my wife (I was at work) we needed a new circuit board even though the unit is only 5 years old... for some reason I don't trust him... here is what happens when the unit is activated... fyi air conditioner works fine... when the heat is activated.. you hear the blower noise, then you smell the gas fumes.. the fan activates but still no heat... I with a little research of my own thought it could be a hot surface igniter or a spark module... ps I have had all the gas connections checked and they are OK... what I am really asking is what are the symptoms of circuit board failure before I take that cash dive? Thanks in advance for your help

what i am really asking is what are the symptoms of circuit board failure before i take that cash dive? thanks in advance for your help

The board is good or bad there is no middle road.

NOTE many boards are under warranty for 5 years or more.

If you have a hot surface igniter and it does not glow then it may be bad, they crack in the middle and you will see a very small white line where the crack is, if you have a spark igniter you will not see a spark or hear a clicking noise and this could be a bad ignition control modual, good luck, Mike