Gas heater makes high-pitched whining noise but it's NOT the blower???

My forced air Gas heater makes a high-pitched whining noise but I'm pretty sure that it's NOT the blower! If anyone has heating a/c savvy, please read on.
We are in a house in Chandler, AZ, that is about 4 years old. It has forced air gas heating. I hear that it's been done cheaply: both the heater and air conditioner are located in the attic (the a/c compressors are outside, the blower etc. are in the attic). People say this is a bad design but cheaper for builders, so we're stuck with it.
We bought the house in during the summer, so we tested the a/c and it works flawlessly. I also tested briefly the heater enough to notice that it worked, but I was so excited looking around our potential new dream home I didn't notice the high pitched squeal it makes.
So around November, when you have to start using the heater in this part of Arizona, I switch the thermostat over to heat and am appalled when I hear this high pitch whining noise that appeared to coincide with the heater. I figured, no problem, it's probably an unlucky small vent in a duct that's making this noise, and I'll just find it and go over it with duct tape. But then I notice that it doesn't coincide with when the blower runs.
Here's its behavior: when the heater lights up to warm the air BEFORE the blower starts, the whine begins. It continues while the blower is blowing, but then about 2 minutes before the blower stops it stops. I assume this is the same time the fire goes out and it stops actively heating while the blower continues to blow over the still hot metal parts.
Does anyone have any idea what is doing this? I could swear it seems to be coming not from the heater itself but from some ductwork about 20 feet away in the attic (inaccessible to me), and this makes no sense to me because as I said, it doesn't start and stop with the blower, so I don't think it's some kind of air movement noise. (I could be mistaken. In the small attic trying to locate the source of the whine is like trying to find a cricket--I can't really tell where its coming from.)
Any ideas?
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possibley the draft inducer motor.

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Many furnaces use a blower to blow air into the combustion chamber. Some use a fan at a distance from the furnace, but also to blow the exhaust through the flue pipe.
Might be the inducer on the furnace, or possibly a fan located in the flue some where. I have a friend who has an inducer fan about 20 feet or so from the furnace, and you can hear the fan through the house.
I'd suggest you follow the flue (chimney) from the furnace, and you'll likely find a blower fan that needs a shot of oil.
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The high-pitched whining you hear is almost certainly from the exhaust fan.
Your furnace has two fans -- a small exhaust fan to make sure there's a draft up the chimney to exhaust the combustion gases, and a large blower fan to blow the air throughout the house. The running of the exhaust fan coincides with when the gas is burning, which is what you described.
It sounds like you've got a failed bearing in the exhaust fan, and it's probably eventually going to fail completely. Ours took at least a year to completely fail after the first time we heard it making bad noises.
If you've got a service plan on the furnace, you can ask them to replace the exhaust fan before it dies completely, but they may say no (they did when my exhaust fan was dying and I asked them to replace it). In that case, you'll have to pay them to replace it early, or wait until it fails, in which case you'll have some period of time with no heat while waiting for them to come replace it (and perhaps a longer time while waiting for them to order the correct fan for your furnace, which is also what happened to us).
Obviously, if you don't have a service plan on the furnace, then you'll have to pay for replacing the fan whether you do it now or when it fails completely, so you'll probably want to do it now for peace of mind.
I'm including your whole article below, because your initial posting had a typo in the Newsgroups line so it didn't actually appear in alt.home.repair....

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Thanks for all the advice. I found what I think is the inducer fan after opening up my Carrier WeatherMaker 8000 (about 4 years old) and oiled it with wd40 where I could reach, but it still makes the noise. Perhaps it is the bad bearings Jonathan Kamens mentions.
BTW, I called Carrier and there is absolutely no technical help of any kind offered. I can understand that with something so potentially dangerous they don't dare give out advice to consumers, but I'm spoiled by computer and software vendors who at least will look up the symptoms and tell you what they know about a model/version. Carrier offers nothing but "here's someone to call in your area."
wrote:

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The problem might be that you used WD. Which is nearly useless for electric motors. Try "Zoom spout turbine oil". Ask for it at the hardware. Comes in a 4 ounce tall plastic bottle, with a spout tube that comes out. Great stuff.
Failing that, try ND-30 or "two stroke" engine oil.
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replying to N Harrison, mimccu wrote:

There could be several reasons for this type of noise. The key is to determine whether it's the electric motor that's going bad or it's something else entirely. I disconnected the PVC pipe (that exhausts to the outside) from the blower motor while the unit was operating to check on the noise source. (Be very careful while doing this and make sure there is extra ventilation in the room....open some windows, etc. and only do this for a very short period). With the exhaust pipe disconnected, the noise went away, so in my case, it was not the electric motor going bad. I found it was simply a poor seal where the plastic blower motor housing mounts to the top of the heater. Over time, the seal moved around and was not airtight, so some air was being pulled through the seal and causing a whistle noise. Buying a whole new blower motor ($300 plus dollars) would likely solve the problem, because you would get new seal tape with the new blower, but I'm pretty sure that seal tape (not sure if that's the proper name for it) would be much less costly. Good luck to all in finding the root cause.
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On Sat, 02 Jan 2016 02:44:01 +0000, mimccu

This was posted on January 24, 2004.
See here: http://www.homeownershub.com/maintenance/gas-heater-makes-high-pitched-whining-noise-but-it-s-not-the-503454-.htm
By now, the guy probably was decapitated by the fan blade, due to bad bearings.
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On 1/2/2016 5:19 AM, snipped-for-privacy@unlisted.moc wrote:

Posted by a guy from example dot com, which is Home Moaners Hub. A web portal to Usenet. The nitwit probably doesn't know what a Usenet is.
- . Christopher A. Young learn more about Jesus . www.lds.org . .
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replying to Paintedcow , mimccu wrote:

http://www.homeownershub.com/maintenance/gas-heater-makes-high-pitched-whining-noise-but-it-s-not-the-503454-.htm

I know it's a very old post. I should have started a new one, since this is a common issue and a lot of sites have pretty poor information on how to diagnose. So many folks just assume it's their fan bearings or blades going bad. On a newer heater (that is less than 8 years old or so), I'd say that is a pretty poor bet.
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