20 scion tc noises when AC is turned on get loud too.

Hello
Firstly, what kind of noise?
1) it could be some thing got into the fan blades and with the fan running = it makes noise.
2) Maybe you got worn out bearings on the fan blades

blown speakers or a noise filter in the power wire has been removed.

Humming Noise Front End- Any Ideas? - Ford Explorer and Ranger ...

www.explorerforum.com > ... > Stock 1995 - 2001 Explorers

Dec 18, 2008 - 19 posts - ‎16 authors
Have a 98- Eddie 4.0 SOHC, 4WD with a 100,000 mi. When driving it has a humming noise, it almost sounds like a bad tire, or a ... I start to hear the humming noise at 20 mph, it is very loud at 40 to 50 mph ... 94 XLT-95 FX4. humming gets louder as speed increases
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check auxiliary fan bearing.

sounds like a c.v. axle is bad.

It is possible that a stray leaf or piece of debris is stuck in the blower fan blades. This is more likely if the noise began suddenly. You will have to access the blower and remove it to inspect the blades. If their isn't an obvious debris problem, the blower fan bearing may be wearing out and getting noisy; although this noise would slowly get worse and worse every day.

is the front axle broken if not you could have differential damage and that is exspensive a trans job but check out the trans oil if its black or smells bad as well try to jack up car and check front axles if they turn or are out of position

If you pull out the glove box you will find the in cabin air filter, you probly want to replace it

Check you wheel bearings and CV joints. Check the inner CV joints also.