falcon64

Hi Guys,
I'm hoping someone here can give some ideas as to what's wrong as I am at my wits end.
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 winter 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 a relay on the fan control board rapidly opening and closing (about every second) , and this would make the whole housing vibrate, then it quit operating all together. It was believed by a local tech that the fan control board was bad. After repalcement it worked fine for a little over a month and started 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! It then 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 relay noise, so I turned main power off and on a few times and it went back to normal operation again. A friend of mine who works for Siemens Building Technologies looked at it and installed a back up relay for the blower motor seemed to take care of the problem for the remainder of last winter. It worked fine this winter until last week when it started acting up again. I'm now convinced this only served as a band aid! Here are the current symptoms: Started out with a normal cycle, but blower motor would not come on, burner would stay llit until it reached limit I assume, and shut off. After turning power off and back on, would somtimes operate for a full cycle and other times the blower motor would cut out prematurely and after turning the stadt all the way down to kill the burner, the relay noise would begin again. And last night it did the weirdest thing, started the normal cycle, blower failed to come on. so I turned the stadt all the way down, shortly after doing this the blower motor came on by itself! I noticed often times if I leave the power off for the night, it will run for fine for two or three cycles before acting up again. This morning, however, the blower fan cut out after about ten minutes of operation. Could this newest control board be going bad already or is there an underlying problem contibuting to this? Sorry this is so long, but I felt a detailed history would help. One more thing, this furnace has no diagnostic indicator lights. This is a very frustrating and expensive situation! Thanks in advance for your time!

HVAC Doc

A hunch says it most likely has a Smart Valve set up. Although it should have the newer Grey topped design, I wouldn't rule it out 100% based on that alone. The older Tan topped ones had many issues. Where is this furnace located? Is the area wet or is there condensation draining back improperly or forming on the unit/components? It may also boil down to calling the original installer as the issue could have a service update/bulletin where others may have experienced the same problems you have. Just tossing out ideas here for you as it is hard to diagnose with certainty sitting in front of my computer and not your furnace

falcon64

HVAC Doc,
Thanks for the reply and your input!
I tried something last night which seemed to help, but I won't get to excited until the furnace has run properly for at least a few days. Ironically enough, as you mentioned, I was told that the electronics are mostiure sensitive and that it can potentially cause functional problems. I noticed some drops of water present in the vicinity of the control board and discovered that the drain for the draft inducer motor had been dripping water from the compression elbow which is situated just before it exits to feed out of the side of the unit and into the drain line . I took it apart and made sure there was no obstructions anywhere, then put it back together making sure both ends were tight. I then positioned a fan so it would blow directly into the area to dry out any moisture that might be present. My basement has pre cast walls and is a relatively dry enviorment. So far it has functioned properly since about 6:00 PM last night. I won't hold my breath though, LOL! This was a last ditch effort on my part. I will be sure and keep you posted. Thanks again!

dacusvillegirl

We refer to them as Comfortmaker and also COmfortjunk. They are honestly the worst brand on the market. I would contact them and they can send out a Tech. from ICP to check out your unit at their cost, if you fuss enough. You can present them with your service history, your current HVAC company that you have been using can provide you with that information.

Bestheating

Inside the Honeywell Smart Valve is a small PC board. The pins which the plugs connect to, push loose from the board itself (solder connections) and you will intermittent connections. A buck says it's the valve. Took me a few years to learn this one, until I finally took a valve apart to see what made it tick. The valve however, except for experimentation should not be messed with. It is not repairable for additional use and once it is cut apart it is junk!
Larry