NOISE FROM FRONT PANEL HEADPHONES+FAN SPEED KNOB

The switch is bad, replace the switch

mcdevito75 here, Sounds like that oscillating swtich is either a little loose or could use a drop or 2 of 3 in 1 oil. Try to twist offf the oscillating swatch button and see if you can tighten it or put a drop of oil on it.

blower switch knob most likely dealer item, shifter boot, both be dealer items

Have you perhaps turned the volume down using the external volume knob on the side or front of the machine? Have you tried the control panel -> audio devices settings to increase speaker volume for WAV devices?[heck, all devices...] Most machines use the same external knob for headphones and the tinny speakers, so that may be a fruitless chase, but give it a try anyway. You could also have a loose connection. Has anyone recently done work on the PC?
tom

There could be dust on the fan causing it to become un ballanced and start causing vibrations through the unit...

If I am thinking of the right sound go back into your audio mixer and turn down or off the mic pre amp or gain. On mine I have two preamp setting and one gives me a squealing sound if enabled.

Usually is labeled "mic boost 2"

Sounds like the fan control knob has shorted out. You can check the fan "blower" relay and fuse in the engine compartment but you need to make sure the control knob is good or you will keep blowing fuses and relays. If your blower fuse and relay are good, then just have the control knob checked and replaced if needed.

is it the temperature control knob or the fan speed knob? the temperature control knob is hooked to a cable that operates a valve in the engine compartment. sounds like this is your trouble area...you can open the hood and locate the heater control valve near the firewall...have someone turn the knob to see if the valve lever opens/closes. if it does it is bad. if it does not move there is a problem in the dashboard behind the heater control unit.

it might be the speaker or it break

this fan is a variable speed and is controlled by a board in the rear of the unit. your bearings maybe going out. The fan will ramp up to speed depending on the call for cooling the Thermistors is asking for