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Gear Motor Noise from Driver's dash when cool


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RE: Our 2000 Seville STS 4.6 Northstar

Have an annoying gear reduction motor (? or something) sound eminating from the driver's side dash front-left of the steering column....appears to be coming from behind a small grille (about 1" diameter) This growling sound goes away after approx. 2 min ...

This noise only happens when outside temps are below approx. 50 degrees- Engine does not have to be running- very annoying and doesn't seem to serve a purpose and no explanation in manuals-

Any idea what is going on?? Has me stumped...I'd like to stop it! Thanks!

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There is a tiny fan in there that pulls cabin air in to measure its temp. The bearings are probably dry and the cold weather probably gums up the old lube and it quiets down as it gets warmed up.

They can go bad, it needs replacing. Its not unlike a noisy cooling fan in your laptop or desktop...

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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There is a tiny fan in there that pulls cabin air in to measure its temp. The bearings are probably dry and the cold weather probably gums up the old lube and it quiets down as it gets warmed up.

They can go bad, it needs replacing. Its not unlike a noisy cooling fan in your laptop or desktop...

Thank you for the information and that may just be the problem. I have removed the left dash

end cap ( requires the drivers door to be open) and can reach in around some duct work and

touch this part and feel the growling activity. Strange as I have been to 2 Caddy parts depts.

and got blow ups of all the parts in this area but no mention of a small fan and in both cases

the parts guys were stumped with this problem.

I am not looking forward to tearing into the dash as I have had to replace the blower motor on

the passenger side twice..what a pain!!!

Thanks again for your prompt response!

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It's called the aspirator.

Ahh that's right

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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  • 2 weeks later...
RE: Our 2000 Seville STS 4.6 Northstar

Have an annoying gear reduction motor (? or something) sound eminating from the driver's side dash front-left of the steering column....appears to be coming from behind a small grille (about 1" diameter) This growling sound goes away after approx. 2 min ...

This noise only happens when outside temps are below approx. 50 degrees- Engine does not have to be running- very annoying and doesn't seem to serve a purpose and no explanation in manuals-

Any idea what is going on?? Has me stumped...I'd like to stop it! Thanks!

The part number is 25640104, named "in-car sensor", available from GM parts direct for about $40 including S/H.

Once fans of that sort start squealing, it's time to replace--it will run slower and slower and eventually stop running altogether. I've tried on numerous occasions to repair similar fans (including one of these) and have never succeeded in getting them to work for any length of time.

Once the fan stops running altogether, you won't hear anymore noises and no DTCs will be set but you'll insist there's a MAJOR problem with the climate control system as it will continually freeze you out--especially in winter when you need heat. Warm air will get trapped in the sensor body and the system will think the car is far warmer than it really is.

Believe it or not, you don't have to "tear into the dash" to replace. First remove the little grille (be careful as it does not come with the sensor). Then remove the driver side dash end cap and side window defroster duct. Then remove the headlight switch (it's a push fit but it will probably be quite snug).

Then, quite deep inside the dash, you'll see a single small hex head screw securing the sensor body. Loosen--DO NOT REMOVE--the nut and the sensor [should] come loose. Once loose you have to manipulate the thing until, all of a sudden, it almost seems to pop out of a hole that looks too small.

Once you have the new sensor into position, re-install the little grille before securing the screw. The grille will help prevent it slipping out of position as you tighten the screw.

Be patient. The first time I replaced one, I thought it was nearly as much a pain as replacing the cabin air filter. The second time, it was a comparative breeze and FAR easier than the cabin air filter which I will simply remove before ever again replacing.

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