Tempermental Forced Air Furnace

falcon64

Hi Guys,
I'm hoping someone here can give some ideas as to what's wrong.
First off this information pertains to an Air Quest (International Comfort Prouducts Corp.) Model# NTGMO75EGA3 90 plus efficiency forced air furnace. The unit was installed new about 6 years ago and up until recently has worked perfectly. Last month it started behaving strangely. At first the draft inducer motor would come on and go off several times before completing ignition and going through a normal cycle. Later that day it got to the point where all you could hear was what sounded like the ignitor snapping. Then it quit operating all together. It was believed that the fan control board was bad. After repalcement it worked fine for a little over a month and yesterday morning it was exibiting the same symptons, However later on the ignitor issue ceased and the draft inducer motor was still cycling on and off before operating properly. Still later that day, when I returned home from work, back it was working fine! This afternoon it started the same sequence except that at one point the burner fired and stayed lit for a minute or 2 without the blower motor running, and then it shut down and starting the pulsating thumping or snapping noise, so I turned main power off and on a few times and it went back to normal operation again. Could the new control board be going bad already or is there an underlying problem contibuting to this? Thanks in advance for your time.

NickTech

as far as a common contributing problem that surrounds your board issue, there is moisture. To the board module moisture is like a labodimy to your brain. it makes it act out of whack so to speak. a 90+ furnace is refered to as a condensing furnace, which means water vapor in the exaust recondenses into liquid, collects and is drained away. there may be a moisture issue revolving around that principle, or some other moisture source, ie. humidifier, damp basement a/c drain, furnace condesate drain etc. before replacing the board again see if the afore mentioned problems are an issue. :Thumbs:

falcon64

Nick,
Thanks for your reply. I do have an April Air humidifier that was installed with the furnace, but when we replaced the board we didn't notice the presence of moisture, although we were'nt looking for that as a possible cause. I will investigate further. Thanks!

falcon64

Update:
When I was at work today, I had the opportunity to ask for advice from one of the maintainence mechanics from Siemens Building Technologies who services the controls in our building, and he came to the house this afternoon and acessed the situation. Of course the furnace ran perfectly for him too. After I explained the symptoms, he looked it over and decided to wire in an auxilary relay for the draft inducer motor in the hopes that that would solve the problem. Keep your fingers crossed!

NickTech

SOUND GREAT, BUT BE AWARE THAT WHAT EVER MADE THE RELAY WITH IN THE BOARD GO, MAY CAUSE SOMETHING ELSE TO GO AS WELL. ALSO MAKE SURE YOUR WARRANTY ISNT VOID BY USING AFTER MARKET COMPONENTS, :Thumbs:

SVENTING

1. You mentioned something very important.. The burners lit, but the main blower did not come on. IF the blower fails to come on themain limit will shut the burners off for safety.

2. If your gas valve has an indicator light, it will flash a cetain sequence.
3. The furnace should have a fault code indentifier to indicate what the flash codes are.