high pitched whining noise from heater

hey guys,
the automatic heater system in my '98 grand prix gt is making a really loud whining noise when i turn it on. It doesn't matter the temperature or strength of air flow i set it to. The air itself seems to be coming out fine, but the noise is unbearable. It did it a couple of times last winter when it was like minus 25 C outside but it stopped after a minute or so. Now it's doing it it when it's not that cold (only minus 5 C) and it won't stop either.
Any idea on the origin of the problem and possible solutions is very much appreciated.

Also, since it's my first post i'd like to thank all you good people who take the time to help out guys like myself. I've learned a lot on this forum the last year or so.
Thanx again

Welcome to the forum. Learned alot here too.

I have heard of insulation or gaskets and duct valve seals comming loose and flapping debris in the duct and logically that proubbly would change it's sound and pitch some as you change blower speeds. My thinking is that a flapping or whistling foreign membrane like celophane of some sort may just like to flap or sing at close to one frequency. Kindof like when I was a kid and put a leaf between my two thumbs and blew to make it whistle. However, even the blower motor might do that, find a frequency it likes to whine at.

You could disconnect and un-power the blower for a test. That might help eliminate or locate a vibrating/cycling relay or something. Electrically horns are sortof a cycling relay buzzer that when it opens it opens its own power to open and closes and finds power and re-opens.. etc very fast. The mechanics and physics of the horn determine its frequency . It is made to buzz and do that.
A actual relay chattering will eventually wear itself out and burn up its contacts.

Just thoughts without being there.

or


Turn the radio way up?
:bs::bs::bs::bs::bs:

The problem with your fan is a bad or worn bearing in the fan motor. You can try to save it by removing the fan assembly and adding oil to the bearing. Sometimes the oil will lubricate it enough to allow you to keep using it. However, if it is as bad as you say you will probably need to replace the entire assembly. Just remember to use one for automatic heating. The manual and automatic fans are different and will not interchange.

If you want to change it yourself, you will need to get way up under the dash on the passenger side. I suggest you remove the seat to get additional room. The fan is held by three small bolts around 5.5 to 6.5 mm. Can't remember which. Remove them and remove the fan. Replace in reverse order. Good Luck!

thank you very much for your help/ideas i really appreciate them.
Tomorrow i'll give it a go.
In case i'm not able to do it myself, do you guys have any idea how much a shop would charge for something like that? Just a rough estimate would do, so i don't get totally taken for a ride.
Thanks again.

Most of us in the U.S. are not familiar with costs up in Canada but shop around and get a few estimates. The important thing to consider is make sure they install the right replacement blower motor. There are two different GM part numbers. One for manual HVAC (RPO code C60/C67) and one for Automatic Climate Control (ACC - RPO code CJ2). The fans have different ratings. Good luck.

sounds good
thanks again for the help guys